According to police sources, a car with a certain protection system will be recovered 90% of the time. If 600 stolen cars are randomly selected, what is the mean and standard deviation of the number of cars recovered
After being stolen?
A)mean: 540; standard deviation: 7.35
B)mean: 540; standard deviation: 54
C)mean: 306: standard deviation: 7.35
D)mean: 306: standard deviation: 54

Question

Quizplus · Accepted Answer

The mean of the number of cars recovered is calculated as 90% of 600, which is 0.90 * 600 = 540. The standard deviation is calculated using the formula for the standard deviation of a binomial distribution, which is sqrt(n*p*(1-p)), where n is the number of trials (600), p is the probability of success (0.90), and (1-p) is the probability of failure (0.10). Thus, the standard deviation is sqrt(600*0.90*0.10) = sqrt(54) = 7.35.

According to Police Sources, a Car with a Certain Protection