Proofs
Geometry
Probability
Algebra
Misc
100

Prove that the diagonals of a triangle are congruent

Check proof

100

what is the volume of a sphere with radius 1?

4/3 pi

100

A fair 6 sided dice and a fair coin is flipped. What is the probability that the coin flips head and the dice doesn't roll a 6. 

5/12

100

Find the sum of the answers of x+x+x=x^3


0

100

what is 1+2*3+4

11

200

Prove the divisibility rule of 3

Check proof

200

Square ABCD has side lengths 1. Points P, Q, R, S each lie on a side of ABCD such that APQCRS is an equilateral convex hexagon with side length s. What is s?

2-sqrt(2)

200

A leap year has 366 days. Find the probability of a year having 53 Sundays if a leap year happens once every four years?

5/28

200

Solve for all x such that

|x+8|+|x-5|=13

-8<=x<=5

200

What is d/dx (e^x)

e^x

300

Prove that 0.99999... = 1

Check proof


300

What is arcsin(sin(4pi/3))

-pi/3

300

Each of two boxes contains three chips numbered 1, 2, 3. A chip is drawn randomly from each box and the numbers on the two chips are multiplied. What is the probability that their product is even?

5/9

300
sqrt(a+sqrt(a+sqrt(a))) = 128


find floor(a)

16256

300

A ball is launched vertically at a speed of x and reaches a height of h. The max height of the ball launched at a speed of 5x can be written as mh. Find m. 

25

400

Prove that (a+b)(b+c)(c+a) >= 8abc

Check Proof

400

On square ABCD, point E lies on side AD and point F lies on side BC such that BE = EF = FD = 30. Find the area of the square.

810

400

Eight people are sitting around a circular table, each holding a fair coin. All eight people flip their coins and those who flip heads stand while those who flip tails remain seated. What is the probability that no two adjacent people will stand?

47/256

400

(sqrt(3)/2 + 1/2i)^12 can be written as a+bi. What is a+b?

1

400

3^32-2^32 has four factors under 100. Find them

5,13,17,97

500

Find and prove the max value of x + 2y + 3z given x² + y² + z² = 1. 

Check proof, max value = sqrt(14)

500

What is the area of a right triangle whose hypotenuse is 10 and altitude to the hypotenuse is 6?

Triangle Does Not Exist!

500

!!!DAILY DOUBLE!!! 

(This question is worth 1,000 points!)

X, Y, and Z are three random real numbers in the range [0,1] each. What is the probability that X+Y+Z  <= 1?

1/6

500

Let f and g be two quadratic polynomials with real coefficients such that the equation f(g(x)) = 0 has four distinct real solutions: 112, 131, 146, and a. Compute the sum of all possible values of a.

389

500

What is the 21st Fibonacci Number?

10946

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