Question

A die is rolled twice. Find the probability that 5 will not come up either time.

Answer 1

Total number of outcomes = 36.

Cases where 5 comes up on at least one time are (1, 5), (2, 5), (3, 5), (4, 5), (5, 1), (5, 2), (5, 3), (5, 4), (5, 5), (5, 6) and (6, 5).

Number of such cases = 11.

Number of cases where 5 will not come up either time = 36 − 11 = 25.

∴ P(5 will not come up either time) = `("Number of favourable outcomes")/"Number of all possible outcomes"`

= `25/36`

Thus, the probability that 5 will not come up either time is `25/36`.