Probability

[jburklund]

You have applied for a summer job at Store A and also at Store B. You estimate that probabilities of getting the job at the stores A and B are 0.1 and 0.7 respectively. You also estimate that the probability of getting both jobs is only 0.04. You may find it helpful to draw an appropriately labeled Venn diagram before you start answering the questions below.

1) What is the probability that you get at least one of the jobs?

P(A) + P(B) - P(A and B)
.1+.7-.04=.76

2) What is the probability that you get exactly one of the jobs?

HELP! According to my textbook, the answer is .72 but I can't figure out how to get there...

3) What is the probability that you get a job at A but not at B?

P(A) - P(A and B)
.1-.04=.06

4) What is the probability that you do not get a job at either of the companies?

HELP! According to my textbook, the answer is .24 but I can't figure out how to get there...

My original calculation is below, but it isn't right...

P(S) - P(A) - P(B)
1-.1-.7=.2

[JohnM]

(2)
= P(A and B') + P(A' and B)
= [ P(A) - P(A and B) ] + [ P(B) - P(A and B) ]
= [ 0.1 - 0.04 ] + [ 0.7 - 0.04 ]
= 0.06 + 0.66
= 0.72

(4)
P(A' and B') = 1 - P(A or B) = 1 - 0.76
= 0.24