Frequent Probability Questions

Two distinct numbers a and b are chosen randomly from the set {2, 22, 23, 24, ......, 225}. Find the probability that logab is an integer. ...

*Image* a)For the first part the expected value would be = E(x)=\frac{1}{2}+2\left(\frac{1}{2}\right)^2+3\left(\frac{1}{2}\right)^3+\cdots=2 b)For the second part the expected value would be = E(x)=\frac{1}{2}+\frac{2}{4}+\fr ...

Consider a 25*25 grid of city streets. Let S be the points of intersection of the streets, and let P be the set of paths from the bottom left corner to the top right corner of which consist of only walking to the right and up ...

A box contains coupons labeled 1,2,3,....n. A coupon is picked at random and the number x is noted. The coupon is put back into the box and a new coupon is picked at random. The new number is y. Then the probability that one ...

When any three points are selected from a circle, what is the probability that they will form an obtuse-angled triangle? ...