A biased die has a probability of 1/4 of showing a 5, while the probability of any of 1, 2, 3, 4, or 6 turning up is the same. If three such dice are rolled, what is the probability of getting a sum of at least 14 without getting a 6 on any die?

Option 1 : 5/24

Option 2 : 9/160

Option 3 : 1/30

Option 4 : 7/160

Question

Blevins

13 November, 09:05

+3

Answers (1)

Know the Answer?

Teagan Reeves · Answer 1

Possibilities of outcomes:

5, 5, 5

5, 5, 4

P (sum at least 14) = P (5,5,4) + P (5,5,5)

= 1/4 x 1/4 x 3/20 + 1/4 x 1/4 x 1/4

1/40