Question

A 12-sided solid has equal-sized faces numbered 1 to 12.
a. Find P(number greater than 10).
b. Find P(number less than 5).
c. If the 12-sided solid is rolled 200 times, how many times would you expect either a 4, 6, or 9 to be rolled?

Answer 1

There are 12 equally likely outcomes (1–12).

a. Numbers > 10 are {11,12}: P = 2/12 = 1/6.

b. Numbers < 5 are {1,2,3,4}: P = 4/12 = 1/3.

c. P(4 or 6 or 9) = 3/12 = 1/4. Expected count in 200 rolls = 200*(1/4) = 50.