Knewton Brutal Math Challenge - Week 6

by , Apr 28, 2010

For those who like their math served brutally. Playing again for the shirt. Show your work.

The "u-number" of a number x is defined as the ones digit of 2^x. Antony rolls a die with 6 sides labeled with the integers from 1 to 6, each of which has an equal probability of landing face-up. He then takes 3^u, where u is the u-number of the result of his die roll, and plots 3^u on a number line as the point A. Finally, he repeats this entire process, this time plotting the result as the point B. What is the probability that the distance between A and B is greater than the value of B?

(A) 3/8

(B) 13/36

(C) 17/36

(D) 19/36

(E) 23/36