Unnamed: 0
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40.3k
problem
stringlengths
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ground_truth
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float64
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100
8,900
Given that the positive numbers $x$ and $y$ satisfy the equation $$3x+y+ \frac {1}{x}+ \frac {2}{y}= \frac {13}{2}$$, find the minimum value of $$x- \frac {1}{y}$$.
- \frac {1}{2}
18.75
8,901
Given that the dihedral angle $\alpha-l-\beta$ is $60^{\circ}$, points $P$ and $Q$ are on planes $\alpha$ and $\beta$ respectively. The distance from $P$ to plane $\beta$ is $\sqrt{3}$, and the distance from $Q$ to plane $\alpha$ is $2 \sqrt{3}$. What is the minimum distance between points $P$ and $Q$?
2\sqrt{3}
14.0625
8,902
Given the complex numbers \( z = \cos \alpha + i \sin \alpha \) and \( u = \cos \beta + i \sin \beta \), and that \( z + u = \frac{4}{5} + \frac{3}{5} i \), find \( \tan(\alpha + \beta) \).
\frac{24}{7}
56.25
8,903
The natural number \(a\) is divisible by 35 and has 75 different divisors, including 1 and \(a\). Find the smallest such \(a\).
490000
4.6875
8,904
Given a sequence $\{a\_n\}$ with its sum of the first $n$ terms denoted as $S\_n$. For any $n ∈ ℕ^∗$, it is known that $S\_n = 2(a\_n - 1)$. 1. Find the general term formula for the sequence $\{a\_n\}$. 2. Insert $k$ numbers between $a\_k$ and $a_{k+1}$ to form an arithmetic sequence with a common difference $d$ such that $3 < d < 4$. Find the value of $k$ and the sum $T$ of all terms in this arithmetic sequence.
144
42.1875
8,905
What is the smallest prime whose digits sum to \(28\)?
1999
0
8,906
How many five-digit numbers divisible by 3 are there that include the digit 6?
12504
78.125
8,907
A child whose age is between 13 and 19 writes his own age after his father's age, creating a four-digit number. The absolute difference between their ages is subtracted from this new number to obtain 4289. What is the sum of their ages? (Note: From the 22nd Annual USA High School Mathematics Examination, 1971)
59
21.875
8,908
In $\triangle ABC$, $a$, $b$, $c$ are the sides opposite to angles $A$, $B$, $C$ respectively, and $B$ is an acute angle. If $\frac{\sin A}{\sin B} = \frac{5c}{2b}$, $\sin B = \frac{\sqrt{7}}{4}$, and $S_{\triangle ABC} = \frac{5\sqrt{7}}{4}$, find the value of $b$.
\sqrt{14}
32.03125
8,909
Find the largest solution to the equation \[\lfloor x \rfloor = 8 + 50 \{ x \},\] where $\{x\} = x - \lfloor x \rfloor.$
57.98
84.375
8,910
The minimum sum of the distances from a point in space to the vertices of a regular tetrahedron with side length 1 is:
$\sqrt{6}$
0
8,911
Given vectors $\overrightarrow{a}=(\sin x,\frac{3}{2})$ and $\overrightarrow{b}=(\cos x,-1)$. $(1)$ When $\overrightarrow{a} \parallel \overrightarrow{b}$, find the value of $\sin 2x$. $(2)$ Find the minimum value of $f(x)=(\overrightarrow{a}+\overrightarrow{b}) \cdot \overrightarrow{b}$ for $x \in [-\frac{\pi}{2},0]$.
-\frac{\sqrt{2}}{2}
85.9375
8,912
Find the times between $8$ and $9$ o'clock, correct to the nearest minute, when the hands of a clock will form an angle of $120^{\circ}$.
8:22
61.71875
8,913
Let \(a\) and \(b\) be positive integers such that \(90 < a + b < 99\) and \(0.9 < \frac{a}{b} < 0.91\). Find \(ab\).
2346
82.03125
8,914
A phone fully charges in 1 hour 20 minutes on fast charge and in 4 hours on regular charge. Fedya initially put the completely discharged phone on regular charge, then switched to fast charge once he found the proper adapter, completing the charging process. Determine the total charging time of the phone, given that it spent one-third of the total charging time on the fast charge. Assume that both fast and regular charging happen uniformly.
144
16.40625
8,915
A class participates in a tree-planting event, divided into three groups. The first group plants 5 trees per person, the second group plants 4 trees per person, and the third group plants 3 trees per person. It is known that the number of people in the second group is one-third of the sum of the number of people in the first and third groups. The total number of trees planted by the second group is 72 less than the sum of the trees planted by the first and third groups. Determine the minimum number of people in the class.
32
4.6875
8,916
In triangle \( \triangle ABC \), given that $$ \angle A = 30^{\circ}, \quad 2 \overrightarrow{AB} \cdot \overrightarrow{AC} = 3 \overrightarrow{BC}^2, $$ find the cosine of the largest angle of \( \triangle ABC \).
-\frac{1}{2}
35.9375
8,917
Given the following propositions: (1) The graph of the function $y=3^{x} (x \in \mathbb{R})$ is symmetric to the graph of the function $y=\log_{3}x (x > 0)$ with respect to the line $y=x$; (2) The smallest positive period of the function $y=|\sin x|$ is $2\pi$; (3) The graph of the function $y=\tan (2x+\frac{\pi}{3})$ is centrally symmetric about the point $\left(-\frac{\pi}{6},0\right)$; (4) The monotonic decreasing interval of the function $y=2\sin \left(\frac{\pi}{3}-\frac{1}{2}x\right), x \in [-2\pi, 2\pi]$ is $\left[-\frac{\pi}{3},\frac{5\pi}{3}\right]$. The correct proposition numbers are $\boxed{(1)(3)(4)}$.
(1)(3)(4)
89.84375
8,918
Given a square \(ABCD\) on the plane, find the minimum of the ratio \(\frac{OA+OC}{OB+OD}\), where \(O\) is an arbitrary point on the plane.
\frac{1}{\sqrt{2}}
3.125
8,919
$15\times 36$ -checkerboard is covered with square tiles. There are two kinds of tiles, with side $7$ or $5.$ Tiles are supposed to cover whole squares of the board and be non-overlapping. What is the maximum number of squares to be covered?
540
39.84375
8,920
Convert the binary number $101101_2$ to an octal number. The result is
55_8
74.21875
8,921
Given that $a$, $b$, $c$, and $d$ are distinct positive integers, and $abcd = 441$, calculate the value of $a+b+c+d$.
32
97.65625
8,922
Calculate $0.25 \cdot 0.08$.
0.02
100
8,923
Three cars leave city $A$ at the same time and travel along a closed path composed of three straight segments $AB, BC$, and $CA$. The speeds of the first car on these segments are 12, 10, and 15 kilometers per hour, respectively. The speeds of the second car are 15, 15, and 10 kilometers per hour, respectively. Finally, the speeds of the third car are 10, 20, and 12 kilometers per hour, respectively. Find the value of the angle $\angle ABC$, knowing that all three cars return to city $A$ at the same time.
90
44.53125
8,924
A three-digit number \( X \) was composed of three different digits, \( A, B, \) and \( C \). Four students made the following statements: - Petya: "The largest digit in the number \( X \) is \( B \)." - Vasya: "\( C = 8 \)." - Tolya: "The largest digit is \( C \)." - Dima: "\( C \) is the arithmetic mean of the digits \( A \) and \( B \)." Find the number \( X \), given that exactly one of the students was mistaken.
798
0
8,925
Beatriz loves odd numbers. How many numbers between 0 and 1000 can she write using only odd digits?
155
35.15625
8,926
In $\triangle ABC$, $\angle B=60^{\circ}$, $AC=2\sqrt{3}$, $BC=4$, then the area of $\triangle ABC$ is $\_\_\_\_\_\_$.
2\sqrt{3}
67.96875
8,927
Given a fair coin is tossed, the probability of heads or tails is both $\frac{1}{2}$. Construct a sequence $\{a_n\}$, where $a_n = \begin{cases} 1, \text{if heads on the nth toss} \\ -1, \text{if tails on the nth toss} \end{cases}$. Let $S_n = a_1 + a_2 + ... + a_n$. Find the probability that $S_2 \neq 0$ and $S_8 = 2$.
\frac{13}{128}
17.96875
8,928
The function $g$, defined on the set of ordered pairs of positive integers, satisfies the following properties: \[ g(x,x) = x, \quad g(x,y) = g(y,x), \quad (x + y) g(x,y) = yg(x, x + y). \] Calculate $g(18,63)$.
126
1.5625
8,929
Given a circle with center \(O\) and radius \(OD\) perpendicular to chord \(AB\), intersecting \(AB\) at point \(C\). Line segment \(AO\) is extended to intersect the circle at point \(E\). If \(AB = 8\) and \(CD = 2\), calculate the area of \(\triangle BCE\).
12
17.1875
8,930
$\_$\_$\_$:20=24÷$\_$\_$\_$=80%=$\_$\_$\_$(fill in the blank with a fraction)=$\_$\_$\_$(fill in the blank with a decimal)
0.8
5.46875
8,931
Yesterday, Sasha cooked soup and added too little salt, requiring additional seasoning. Today, he added twice as much salt as yesterday, but still had to season the soup additionally, though with half the amount of salt he used for additional seasoning yesterday. By what factor does Sasha need to increase today's portion of salt so that tomorrow he does not have to add any additional seasoning? (Each day Sasha cooks the same portion of soup.)
1.5
0.78125
8,932
Determine the number of distinct terms in the simplified expansion of $[(x+5y)^3(x-5y)^3]^{3}$.
10
30.46875
8,933
Let $\{a_n\}_{n=1}^{\infty}$ and $\{b_n\}_{n=1}^{\infty}$ be sequences of integers such that $a_1 = 20$ , $b_1 = 15$ , and for $n \ge 1$ , \[\left\{\begin{aligned} a_{n+1}&=a_n^2-b_n^2, b_{n+1}&=2a_nb_n-b_n^2 \end{aligned}\right.\] Let $G = a_{10}^2-a_{10}b_{10}+b_{10}^2$ . Determine the number of positive integer factors of $G$ . *Proposed by Michael Ren*
525825
0
8,934
In a certain class of Fengzhong Junior High School, some students participated in a study tour and were assigned to several dormitories. If each dormitory accommodates 6 people, there are 10 students left without a room. If each dormitory accommodates 8 people, one dormitory has more than 4 people but less than 8 people. The total number of students in the class participating in the study tour is ______.
46
64.0625
8,935
Given that $\lg 2 = 0.3010$, determine the number of digits in the integer $2^{2015}$.
607
100
8,936
If the inequality $x^{2}+ax+1 \geqslant 0$ holds for all $x \in (0, \frac{1}{2}]$, find the minimum value of $a$.
-\frac{5}{2}
67.96875
8,937
Let $a$, $b$, $c$ be the three sides of a triangle, and let $\alpha$, $\beta$, $\gamma$ be the angles opposite them. If $a^2 + b^2 = 2020c^2$, determine the value of \[\frac{\cot \gamma}{\cot \alpha + \cot \beta}.\]
1009.5
3.90625
8,938
Let $(x^2+1)(2x+1)^9 = a_0 + a_1(x+2) + a_2(x+2)^2 + \ldots + a_{11}(x+2)^{11}$, then calculate the value of $a_0 + a_1 + a_2 + \ldots + a_{11}$.
-2
91.40625
8,939
The first term of a sequence is 934. Each following term is equal to the sum of the digits of the previous term, multiplied by 13. Find the 2013th term of the sequence.
130
59.375
8,940
Compute $\oplus(\oplus(2,4,5), \oplus(3,5,4), \oplus(4,2,5))$, where $\oplus(x,y,z) = \frac{x+y-z}{y-z}$.
\frac{10}{13}
71.875
8,941
Given that \( a, b, c, d \) are prime numbers (they can be the same), and \( abcd \) is the sum of 35 consecutive positive integers, find the minimum value of \( a + b + c + d \).
22
4.6875
8,942
Through the vertices \(A\), \(C\), and \(D_1\) of a rectangular parallelepiped \(ABCD A_1 B_1 C_1 D_1\), a plane is drawn forming a dihedral angle of \(60^\circ\) with the base plane. The sides of the base are 4 cm and 3 cm. Find the volume of the parallelepiped.
\frac{144 \sqrt{3}}{5}
7.03125
8,943
Two isosceles triangles each have at least one angle that measures $70^{\circ}$. In the first triangle, the measure in degrees of each of the remaining two angles is even. In the second triangle, the measure in degrees of each of the remaining two angles is odd. Let $S$ be the sum of the equal angles in the first triangle, and let $T$ be the sum of the equal angles in the second triangle. Calculate $S+T$.
250
18.75
8,944
Given positive integers \( a, b, \) and \( c \) such that \( a < b < c \). If the product of any two numbers minus 1 is divisible by the third number, what is \( a^{2} + b^{2} + c^{2} \)?
38
84.375
8,945
The route from $A$ to $B$ is traveled by a passenger train 3 hours and 12 minutes faster than a freight train. In the time it takes the freight train to travel from $A$ to $B$, the passenger train travels 288 km more. If the speed of each train is increased by $10 \mathrm{km} / h$, the passenger train would travel from $A$ to $B$ 2 hours and 24 minutes faster than the freight train. Determine the distance from $A$ to $B$.
360
31.25
8,946
An old clock's minute and hour hands overlap every 66 minutes of standard time. Calculate how much the old clock's 24 hours differ from the standard 24 hours.
12
10.15625
8,947
How many eight-digit numbers can be written using only the digits 1, 2, and 3 such that the difference between any two adjacent digits is 1?
32
94.53125
8,948
There are $15$ (not necessarily distinct) integers chosen uniformly at random from the range from $0$ to $999$ , inclusive. Yang then computes the sum of their units digits, while Michael computes the last three digits of their sum. The probability of them getting the same result is $\frac mn$ for relatively prime positive integers $m,n$ . Find $100m+n$ *Proposed by Yannick Yao*
200
37.5
8,949
In $\triangle ABC$, $a$, $b$, and $c$ are the sides opposite to angles $A$, $B$, and $C$ respectively, and it is given that $a\sin B=-b\sin \left(A+ \frac {\pi}{3}\right)$. $(1)$ Find $A$; $(2)$ If the area of $\triangle ABC$, $S= \frac { \sqrt {3}}{4}c^{2}$, find the value of $\sin C$.
\frac { \sqrt {7}}{14}
0
8,950
In a store where all items cost an integer number of rubles, there are two special offers: 1) A customer who buys at least three items simultaneously can choose one item for free, whose cost does not exceed the minimum of the prices of the paid items. 2) A customer who buys exactly one item costing at least $N$ rubles receives a 20% discount on their next purchase (regardless of the number of items). A customer, visiting this store for the first time, wants to purchase exactly four items with a total cost of 1000 rubles, where the cheapest item costs at least 99 rubles. Determine the maximum $N$ for which the second offer is more advantageous than the first.
504
6.25
8,951
Evaluate $\lfloor 3.998 \rfloor + \lceil 7.002 \rceil$.
11
10.15625
8,952
Given that the probability of player A winning a single game is $\frac{2}{3}$, calculate the probability that A wins the match with a score of 3:1 in a best of five games format.
\frac{8}{27}
50.78125
8,953
Given the function $f(x) = \frac{1}{2}x^2 - 2ax + b\ln(x) + 2a^2$ achieves an extremum of $\frac{1}{2}$ at $x = 1$, find the value of $a+b$.
-1
14.84375
8,954
In an isosceles triangle, the center of the inscribed circle divides the altitude in the ratio $17: 15$. The base is 60. Find the radius of this circle.
7.5
40.625
8,955
Given vectors \(\overrightarrow{O P}=\left(2 \cos \left(\frac{\pi}{2}+x\right),-1\right)\) and \(\overrightarrow{O Q}=\left(-\sin \left(\frac{\pi}{2}- x\right), \cos 2 x\right)\), and the function \(f(x)=\overrightarrow{O P} \cdot \overrightarrow{O Q}\). If \(a, b, c\) are the sides opposite angles \(A, B, C\) respectively in an acute triangle \( \triangle ABC \), and it is given that \( f(A) = 1 \), \( b + c = 5 + 3 \sqrt{2} \), and \( a = \sqrt{13} \), find the area \( S \) of \( \triangle ABC \).
15/2
39.0625
8,956
In $\triangle ABC$, point $M$ lies inside the triangle such that $\angle MBA = 30^\circ$ and $\angle MAB = 10^\circ$. Given that $\angle ACB = 80^\circ$ and $AC = BC$, find $\angle AMC$.
70
53.90625
8,957
If $\left(2x-a\right)^{7}=a_{0}+a_{1}(x+1)+a_{2}(x+1)^{2}+a_{3}(x+1)^{3}+\ldots +a_{7}(x+1)^{7}$, and $a_{4}=-560$.<br/>$(1)$ Find the value of the real number $a$;<br/>$(2)$ Find the value of $|a_{1}|+|a_{2}|+|a_{3}|+\ldots +|a_{6}|+|a_{7}|$.
2186
35.9375
8,958
Given that the eccentricity of the ellipse $C:\frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}=1(a > b > 0)$ is $\frac{\sqrt{2}}{2}$, and it passes through the point $P(\sqrt{2},1)$. The line $y=\frac{\sqrt{2}}{2}x+m$ intersects the ellipse at two points $A$ and $B$. (1) Find the equation of the ellipse $C$; (2) Find the maximum area of $\triangle PAB$.
\sqrt{2}
44.53125
8,959
If the sum of all binomial coefficients in the expansion of $(2x- \frac {1}{x^{2}})^{n}$ is $64$, then $n=$ \_\_\_\_\_\_; the constant term in the expansion is \_\_\_\_\_\_.
240
65.625
8,960
Given the hyperbola $\frac{x^{2}}{a-3} + \frac{y^{2}}{2-a} = 1$, with foci on the $y$-axis and a focal distance of $4$, determine the value of $a$. The options are: A) $\frac{3}{2}$ B) $5$ C) $7$ D) $\frac{1}{2}$
\frac{1}{2}
90.625
8,961
The median to a 10 cm side of a triangle has length 9 cm and is perpendicular to a second median of the triangle. Find the exact value in centimeters of the length of the third median.
3\sqrt{13}
4.6875
8,962
Given the function $f(x)=4\cos(3x+\phi)(|\phi|<\frac{\pi}{2})$, its graph is symmetrical about the line $x=\frac{11\pi}{12}$. When $x_1,x_2\in(-\frac{7\pi}{12},-\frac{\pi}{12})$, $x_1\neq x_2$, and $f(x_1)=f(x_2)$, find $f(x_1+x_2)$.
2\sqrt{2}
65.625
8,963
$ABCD$ is a square that is made up of two identical rectangles and two squares of area $4 \mathrm{~cm}^{2}$ and $16 \mathrm{cm}^{2}$. What is the area, in $\mathrm{cm}^{2}$, of the square $ABCD$?
36
92.96875
8,964
Car X is traveling at a constant speed of 90 km/h and has a length of 5 meters, while Car Y is traveling at a constant speed of 91 km/h and has a length of 6 meters. Given that Car Y starts behind Car X and eventually passes Car X, calculate the length of time between the instant when the front of Car Y is lined up with the back of Car X and the instant when the back of Car Y is lined up with the front of Car X.
39.6
84.375
8,965
Given that the positive integers \( a, b, c \) satisfy \( 2017 \geqslant 10a \geqslant 100b \geqslant 1000c \), find the number of possible triples \( (a, b, c) \).
574
85.15625
8,966
In a student speech competition held at a school, there were a total of 7 judges. The final score for a student was the average score after removing the highest and the lowest scores. The scores received by a student were 9.6, 9.4, 9.6, 9.7, 9.7, 9.5, 9.6. The mode of this data set is _______, and the student's final score is _______.
9.6
39.84375
8,967
Express $\sqrt{a} \div \sqrt{b}$ as a common fraction, given: $$\frac{{\left(\frac{1}{3}\right)}^2 + {\left(\frac{1}{4}\right)}^2}{{\left(\frac{1}{5}\right)}^2 + {\left(\frac{1}{6}\right)}^2} = \frac{25a}{61b}$$
\frac{5}{2}
42.1875
8,968
How many perfect squares are between 100 and 500?
12
0
8,969
The exchange rate of the cryptocurrency Chukhoyn was one dollar on March 1, and then increased by one dollar each day. The exchange rate of the cryptocurrency Antonium was also one dollar on March 1, and then each day thereafter, it was equal to the sum of the previous day's rates of Chukhoyn and Antonium divided by their product. How much was Antonium worth on May 31 (which is the 92nd day)?
92/91
0
8,970
At the 4 PM show, all the seats in the theater were taken, and 65 percent of the audience was children. At the 6 PM show, again, all the seats were taken, but this time only 50 percent of the audience was children. Of all the people who attended either of the shows, 57 percent were children although there were 12 adults and 28 children who attended both shows. How many people does the theater seat?
520
38.28125
8,971
Masha talked a lot on the phone with her friends, and the charged battery discharged exactly after a day. It is known that the charge lasts for 5 hours of talk time or 150 hours of standby time. How long did Masha talk with her friends?
126/29
21.09375
8,972
Given $tan({θ+\frac{π}{{12}}})=2$, find $sin({\frac{π}{3}-2θ})$.
-\frac{3}{5}
22.65625
8,973
Given that $x_{1}$ and $x_{2}$ are two real roots of the one-variable quadratic equation $x^{2}-6x+k=0$, and (choose one of the conditions $A$ or $B$ to answer the following questions).<br/>$A$: $x_1^2x_2^2-x_1-x_2=115$;<br/>$B$: $x_1^2+x_2^2-6x_1-6x_2+k^2+2k-121=0$.<br/>$(1)$ Find the value of $k$;<br/>$(2)$ Solve this equation.
-11
11.71875
8,974
Evaluate: $6 - 8\left(9 - 4^2\right) \div 2 - 3.$
31
92.96875
8,975
In the geometric sequence $\{a_n\}$ with a common ratio greater than $1$, $a_3a_7=72$, $a_2+a_8=27$, calculate $a_{12}$.
96
25
8,976
Given that $x^2+x-6$ is a factor of the polynomial $2x^4+x^3-ax^2+bx+a+b-1$, find the value of $a$.
16
75.78125
8,977
Calculate the area of the parallelogram formed by the vectors \( a \) and \( b \). $$ \begin{aligned} & a = p - 4q \\ & b = 3p + q \\ & |p| = 1 \\ & |q| = 2 \\ & \angle(p, q) = \frac{\pi}{6} \end{aligned} $$
13
86.71875
8,978
Given that point $P$ lies on the ellipse $\frac{x^2}{25} + \frac{y^2}{9} = 1$, and $F\_1$, $F\_2$ are the foci of the ellipse with $\angle F\_1 P F\_2 = 60^{\circ}$, find the area of $\triangle F\_1 P F\_2$.
3 \sqrt{3}
89.0625
8,979
Calculate the value of $v_4$ for the polynomial $f(x) = 12 + 35x - 8x^2 + 79x^3 + 6x^4 + 5x^5 + 3x^6$ using the Horner's method when $x = -4$.
220
49.21875
8,980
A toy store sells a type of building block set: each starship is priced at 8 yuan, and each mech is priced at 26 yuan. A starship and a mech can be combined to form an ultimate mech, which sells for 33 yuan per set. If the store owner sold a total of 31 starships and mechs in one week, earning 370 yuan, how many starships were sold individually?
20
25.78125
8,981
Each of the integers 226 and 318 has digits whose product is 24. How many three-digit positive integers have digits whose product is 24?
21
94.53125
8,982
In the center of a circular field, there is a geologists' house. Eight straight roads radiate from it, dividing the field into 8 equal sectors. Two geologists set off on a journey from their house, each traveling at a speed of 4 km/h along a road chosen at random. Determine the probability that the distance between them will be more than 6 km after one hour.
0.375
3.125
8,983
Find the number of sequences consisting of 100 R's and 2011 S's that satisfy the property that among the first \( k \) letters, the number of S's is strictly more than 20 times the number of R's for all \( 1 \leq k \leq 2111 \).
\frac{11}{2111} \binom{2111}{100}
3.90625
8,984
Given that $\tan \alpha = 2$, find the value of $\frac{2 \sin \alpha - \cos \alpha}{\sin \alpha + 2 \cos \alpha}$.
\frac{3}{4}
100
8,985
Let \( m \) be the product of all positive integer divisors of 360,000. Suppose the prime factors of \( m \) are \( p_{1}, p_{2}, \ldots, p_{k} \), for some positive integer \( k \), and \( m = p_{1}^{e_{1}} p_{2}^{e_{2}} \cdot \ldots \cdot p_{k}^{e_{k}} \), for some positive integers \( e_{1}, e_{2}, \ldots, e_{k} \). Find \( e_{1} + e_{2} + \ldots + e_{k} \).
630
90.625
8,986
If the sequence \(\{a_n\}\) satisfies \(a_1 = \frac{2}{3}\) and \(a_{n+1} - a_n = \sqrt{\frac{2}{3} \left(a_{n+1} + a_n\right)}\), then find the value of \(a_{2015}\).
1354080
0
8,987
Determine the number of prime dates in a non-leap year where the day and the month are both prime numbers, and the year has one fewer prime month than usual.
41
2.34375
8,988
In the rectangular coordinate system $(xOy)$, there are two curves $C_1: x + y = 4$ and $C_2: \begin{cases} x = 1 + \cos \theta \\ y = \sin \theta \end{cases}$ (where $\theta$ is a parameter). Establish a polar coordinate system with the coordinate origin $O$ as the pole and the positive semi-axis of $x$ as the polar axis. (I) Find the polar equations of the curves $C_1$ and $C_2$. (II) If the line $l: \theta = \alpha (\rho > 0)$ intersects $C_1$ and $C_2$ at points $A$ and $B$ respectively, find the maximum value of $\frac{|OB|}{|OA|}$.
\frac{1}{4}(\sqrt{2} + 1)
0
8,989
In a certain country, the airline system is arranged so that each city is connected by airlines to no more than three other cities, and from any city, it's possible to reach any other city with no more than one transfer. What is the maximum number of cities that can exist in this country?
10
57.8125
8,990
The expression $\frac{\cos 85^{\circ} + \sin 25^{\circ} \cos 30^{\circ}}{\cos 25^{\circ}}$ simplify to a specific value.
\frac{1}{2}
29.6875
8,991
There are four different passwords, $A$, $B$, $C$, and $D$, used by an intelligence station. Each week, one of the passwords is used, and each week it is randomly chosen with equal probability from the three passwords not used in the previous week. Given that the password used in the first week is $A$, find the probability that the password used in the seventh week is also $A$ (expressed as a simplified fraction).
61/243
78.125
8,992
In the Cartesian coordinate system, the parametric equations of curve $C_{1}$ are $\left\{{\begin{array}{l}{x=-\sqrt{3}t}\\{y=t}\end{array}}\right.$ ($t$ is the parameter), and the parametric equations of curve $C_{2}$ are $\left\{{\begin{array}{l}{x=4\cos\theta}\\{y=4\sin\theta}\end{array}}\right.$ ($\theta$ is the parameter). Establish a polar coordinate system with the coordinate origin as the pole and the positive x-axis as the polar axis.<br/>$(1)$ Find the polar coordinate equations of $C_{1}$ and $C_{2}$;<br/>$(2)$ Let the coordinates of point $P$ be $\left(1,0\right)$, a line $l$ passes through point $P$, intersects $C_{2}$ at points $A$ and $B$, and intersects $C_{1}$ at point $M$. Find the maximum value of $\frac{{|{PA}|⋅|{PB}|}}{{|{PM}|}}$.
30
20.3125
8,993
Given $x, y, z \in \mathbb{R}$ and $x^{2}+y^{2}+z^{2}=25$, find the maximum and minimum values of $x-2y+2z$.
-15
66.40625
8,994
Let \( m \) be the largest positive integer such that for every positive integer \( n \leqslant m \), the following inequalities hold: \[ \frac{2n + 1}{3n + 8} < \frac{\sqrt{5} - 1}{2} < \frac{n + 7}{2n + 1} \] What is the value of the positive integer \( m \)?
27
21.09375
8,995
Find the smallest natural number that leaves a remainder of 2 when divided by 3, 4, 6, and 8.
26
97.65625
8,996
A \(101 \times 101\) grid is given, where all cells are initially colored white. You are allowed to choose several rows and paint all the cells in those rows black. Then, choose exactly the same number of columns and invert the color of all cells in those columns (i.e., change white cells to black and black cells to white). What is the maximum number of black cells that the grid can contain after this operation?
5100
26.5625
8,997
Calculate the value of the following expressions: 1. $\sqrt[4]{(3-\pi )^{4}}+(0.008)\;^{- \frac {1}{3}}-(0.25)\;^{ \frac {1}{2}}×( \frac {1}{ \sqrt {2}})^{-4}$ 2. $\log _{3} \sqrt {27}-\log _{3} \sqrt {3}-\lg 625-\lg 4+\ln (e^{2})- \frac {4}{3}\lg \sqrt {8}$
-1
63.28125
8,998
A point A is a fixed point on the circumference of a circle with a perimeter of 3. If a point B is randomly selected on the circumference, the probability that the length of the minor arc is less than 1 is ______.
\frac{2}{3}
14.84375
8,999
In a right triangle, the length of one leg $XY$ is $30$ units, and the hypotenuse $YZ$ is $34$ units. Find the length of the second leg $XZ$, and then calculate $\tan Y$ and $\sin Y$.
\frac{8}{17}
73.4375