Question

Each time Caroline goes shopping she decides whether or not to buy fruit.

The probability that she does buy fruit is 0.6.
Independently, she then decides whether or not to buy a CD, with a probability of 0.2 that she does buy a CD.
Work out the probability that she buys fruit or buys a CD or both.

Answer 1

this probability is 0.68

Explanation:

the probability she buys fruit but not a CD is

0.6 × (1 - 0.2) = 0.48

the probability she buys a CD by not fruit is

0.2 × (1 - 0.6) = 0.08

the probability that she buys both is

0.6 × 0.2 = 0.12

the probability that she buys fruit or a CD or both is adding all 3 probabilities :

0.48 + 0.08 + 0.12 = 0.68