Question

A pair of dice is rolled once. find the probability of obtaining a sum of 10 or doubles (same number on both dice).

Answer 1

There are total 36 outcomes when we rolled a pair of dice.

There are 3 outcomes showing sum of 10 and these outcomes are, { (4, 6), (5, 5), (6, 4) }

There are 6 outcomes showing doubles and these outcomes are, {(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6) }

There is only one outcomes showing sum of 10 and double and this outcome is, { (5, 5) }

We want to find, P(sum of 10 or doubles)

P(sum of 10 or doubles)

= P(sum of 10) + P(doubles) - P(sum of 10 and doubles)

= ( 3/36 ) + ( 6/36 ) - ( 1/36 )

= ( 3 + 6 - 1)/36

= 8/36

= 0.2222

Therefore, required probability is 0.2222