Each laptop manufactured by a large electronics company has

Each laptop manufactured by a large electronics company has a probability of 0.001 of being defective. Fifty laptops are randomly selected from the production line of this company. X is a random variable Which counts the number out of the selected laptops which are not defective. Which of the following statements is true? A) X is not binomial because the number of trials is not fixed. B) X is binomial with parameters n = 50 and p = 0.999 C) X is binomial with parameters n = 50 and p = 0.001 D) X is binomial with expected value equal to 25.

Solution

X follows binomial distribution

p = proportion of laptops not defective = 1- 0.001 = 0.999

expected value = np = 50 * 0.999 = 49.95

hence the correct choice is

B) X is binomial with parameters n =50 and p= 0.999