SOLUTION: During February the probability that Fred's car fails to start in the morning is 0.2 and this is unaffected by whether or not it started the previous day. When it fails to start, h

Algebra ->  Probability-and-statistics -> SOLUTION: During February the probability that Fred's car fails to start in the morning is 0.2 and this is unaffected by whether or not it started the previous day. When it fails to start, h      Log On


   

Question 812907: During February the probability that Fred's car fails to start in the morning is 0.2 and this is unaffected by whether or not it started the previous day. When it fails to start, he walks to work.
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(i) What is the probability that Wednesday is the first day of the week (starting on Monday) that he has to walk?
(ii) What is the probability that he drives to work every day from Monday to Friday?
(iii) What is the probability that he drives to work for exactly 4 days in a week?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

Note: The probability of x successes in n trials is: 

P = nCx* p%5Ex%2Aq%5E%28n-x%29 where p and q are the probabilities of success and failure respectively. 

In this case p = .2 & q =.8

nCx = n%21%2F%28x%21%28n-x%29%21%29

P(1 of 3 days) = %283%21%2F%281%212%21%29%29%28.2%29%5E1%28.8%29%5E2 = .3840

P(0 of 5 days) = %285%21%2F5%21%29%28.2%29%5E0%28.8%29%5E5= .3277

P(1 of 5 days) = %285%21%2F4%21%29%28.2%29%5E1%28.8%29%5E4= .4096