Question

According to a survey published by ComPsych Corporation, 54% of all workers read e-mail while they are talking on the phone. Suppose that 20% of those who read e-mail while they are talking on the phone write personal "to-do" lists during meetings. Assuming that these figures are true for all workers, if a worker is randomly selected, determine the following probabilities:

a. The worker does not write personal "to-do" lists given that he reads e-mail while talking on the phone.
b. The worker does not write personal "to-do" lists given that he reads e-mail while talking on the phone.
c. The worker does not write personal "to-do" lists and does read e-mail while talking on the phone.

Answer 1

The probability of the worker does not write personal "to-do" lists given that he reads e-mail while talking on the phone is P=0.8.

Explanation:

a) The worker does not write personal "to-do" lists (
`\bar W`) given that he reads e-mail while talking on the phone (
`R`):

`P(\bar W|R)=1-P(W|R)=1-0.2=0.8`

If it is given that he reads e-mail, we pick out of the 54% of the workers. In this group of workers, 20% write to-do list, so it means that 80% doesn't write to-do lists.