Question

Service calls arriving at an electric company follow a Poisson distribution with an average arrival rate of 5656 per hour. Find the average and standard deviation of the number of service calls in a 1515-minute period. Round your answer to three decimal places, if necessary.

Answer 1

Answer:

The average number of service calls in a 15-minute period is of 14, with a standard deviation of 3.74.

Step-by-step explanation:

In a Poisson distribution, the probability that X represents the number of successes of a random variable is given by the following formula:

$P(X = x) = \frac{e^{-\mu}*\mu^{x}}{(x)!}$

In which

x is the number of sucesses

e = 2.71828 is the Euler number

$\mu$ is the mean in the given interval. The variance is the same as the mean.

Average rate of 56 calls per hour:

This means that $\mu = 56n$, in which n is the number of hours.

Find the average and standard deviation of the number of service calls in a 15-minute period.

15 minute is one fourth of a hour, which means that $n = \frac{1}{4}$. So

$\mu = 56n = \frac{56}{4} = 14$

The variance is also 14, which means that the standard deviation is $\sqrt{14} = 3.74$

The average number of service calls in a 15-minute period is of 14, with a standard deviation of 3.74.