Question

there is a six sided die, number 1- to 6. what is the probability that it it take exactly two tries to roll a 4? what is the expected waiting time until and odd prime number is rolled?

Answer 1

what is the probability of not getting a four on the first try and a 4 on the second.

Pr=5/6 * 1/6

odd prime number? 1,3, 5, ?

expected waiting time? Don't know, what is the time for each roll?

Prob one roll=3/6
since this is 1/2, then one should "expect" a prime number in the first roll.