Question

1. A pair of dice is rolled: one is blue and the other one is white. Find the probability of obtaining:

a. number four on blue AND number five on white.

b. number four on blue OR number five on white.

c.Number two on white AND the sum is odd.

d. Number two on white OR the sum is odd.

e. a sum of 9.

f. a sum of 10.

g. a sum of 11.

h. a sum of 8 or more.

i. Both dice have the same number.

j. The dice have different numbers.

Answer 1

Only 4 subparts per post allowed.

OR is equivalent to adding probabilities.

AND is equivalent to multiplying them.

a. P(4 on blue and 5 on white) = 1/6 × 1/6 = 1/36

b. P(4 on blue or 5 on white) = 1/6 + 1/6 = 1/3

c. If 2 is on white, then for sum to be odd, blue must have 1,3, or 5.

So P(2 on white and sum is odd)= P(2 on white and 1,3or5 on blue) = 1/6 × 3/6 = 1/12

d. The sum can be odd for half of the 36 outcomes.

P(2 on white or sum is odd) = 1/6 + 1/2 = 2/3