Statistic Questin 3

QUESTION THREE

i)?????????????? If 5% of the items produced turn out to be defective. Then find out the probability that out of 25 items selected at random there are

a)???????????? Exactly three defective?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? (3 marks)

b)?????????? At least two defective???????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????(3 Marks)

c)???????????? Exactly four defective???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? (3 marks)

d)?????????? Find the mean and the variance?????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????(3 Marks)

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ii)?????????? Bank customer arrive randomly on a week day afternoon at an average of 3.2 customers every 4 minutes

a)???????????? What is the probability of having more than 7 customers arriving at the bank in an interval of 4 minutes??????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????? ?????????????????????? (4 marks)

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b)?????????? What is the standard deviation of the number of customers arriving in a 4 minutes interval??????????????? ?????????????????????????????????? ?????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????? (4 marks)?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??

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