Question

Assume you roll a die 4 times. What is the probability that you will get exactly one 6 ?

Answer 1

Total ways in which a 6-sided die can be rolled four times = 6*6*6*6 = 1296

To get exactly one 6, there are four ways:
A 6 on the first roll and non 6 on other three rolls. This can be done in 1*5*5*5 = 125 ways.
The 6 could be on the second or third or fourth roll too. So total favorable cases = 125*4= 500

Required Probability = 500/1296 = 125/324