# Probability problem

• Jan 17th 2011, 04:11 PM
terminator
Probability problem
On a cold winter morning in Alaska, the probability that Emery's car will start is 0.45 and the probability that Diana's car will start 0.62

What is the probability that neither car will start?

0.45 X 0.62 = 0.279? - both cars will start (P(A and B) = P(A) x P(B)?
0.45 x 0.38 = 0.17 - start Emery and not start Diana
0.55 x 0.62 = 0.341
0.55 x 0.38 = 0.209( that both will not start)

Need feedback.
Thanks
• Jan 17th 2011, 08:25 PM
bjm
I believe you are correct.
• Jan 18th 2011, 06:08 AM
CaptainBlack
Quote:

Originally Posted by terminator
On a cold winter morning in Alaska, the probability that Emery's car will start is 0.45 and the probability that Diana's car will start 0.62

What is the probability that neither car will start?

0.45 X 0.62 = 0.279? - both cars will start (P(A and B) = P(A) x P(B)?
0.45 x 0.38 = 0.17 - start Emery and not start Diana
0.55 x 0.62 = 0.341
0.55 x 0.38 = 0.209( that both will not start)

Need feedback.
Thanks

The probability that E's car will not start is 1-0.45=0.55

The probability that D's car will not start is 1-0.62=0.38

Now assuming that the cars starting /not starting are independent the probability that neither start is 0.55x0.38=0.209

Note the required assumption is so unlikely as to make the question ludicrous

CB