Question

Twenty percent (20%) of a certain type of cell phones are returned for repairs while under warranty.

(i) If a company purchases ten of these cell phones for their employees, what is the probability that exactly two of them will need repairs while under warranty? [6 marks]

(ii) Of the 10 cell phones purchased by the company, how many would you expect to be returned for repairs while under warranty? [1 mark]

(iii) Suppose five hundred (500) cell phones were purchased by the company, find the probability that more that 80 cell phones would be returned for repairs while under warranty. [6 marks]

(b) (i) List the three (3) conditions characterized by the Poisson process. [3 marks]

(ii) If a bank receives on average 6 bad checks per day, what is the probability that the bank will receive 9 bad checks in any given 2 days? Define the random variable for this experiment. [5 marks]

(d) A bank executive drives from his home to his office. The driving times are normally distributed with a mean of 34 minutes and a standard deviation of 7 minutes. What percentage of the times will it take him 25 minutes or less to drive to work?

Answer 1

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