Answer:
See below in bold.
Step-by-step explanation:
A. On one roll the possible ways to get a sum of 5 is (2,3, ) and (4, 1).
There are 36 possible outcomes from the one roll of the 2 dice.
So the probability of getting a sum of 5 on one roll = 2/36 = 1/18.
So the probability of 5 on 4 rolls = (1/18)^4
= 1/104976.
B.
The probability of the first 3 rolls being a 5 and the last one being not 5
= (1/18)^3 * (17/18)
= 17/104976
There are 4 ways to pick 3 out of 4 so the required probability
= 4 * 17/104976
= 68/104976.
