Question

A computer software vendor wants to estimate the number of times a computer will crash with its new operating system over the course of a year. A system administrator installs the operating system on a random sample of 34 computers. At the end of a year, the sample mean number of crashes is 5.6, with a standard deviation of 2.2. Find the confidence interval at a 90% confidence level for the mean number of crashes a computer will have with the new operating system over the course of a year.

Answer 1

(4.9793, 6.2207)

Explanation:

Given the data:

Sample size, n = 34

Sample mean, m = 5.6

Standard deviation, s = 2.2

Confidence interval = 90%

Using the relation :

m ± Zcritical * s/√n

Zcritical at 90% confidence interval = 1.645

Confidence interval ;

5.6 ± (1.645 * 2.2/√34)

5.6 ± 0.6206533

Lower boundary = 5.6 - 0.6206533 = 4.9793

Upper boundary = 5.6 + 0.6206533 = 6.2207