# Confidence interval for mean

5. A researcher wants to estimate the mean number of hours (mu) ; children watch television per day. A sample of 38 children is taken. The sample mean is 6.8 hours with a sample standard deviation of 1.1 hours.

a. Find the 90% confidence interval for mean (mu).

b. Find the 95% confidence interval for mean (mu).

https://brainmass.com/statistics/confidence-interval/finding-confidence-interval-mean-number-hours-246737

#### Solution Preview

5. Data:

Sample mean= Xbar = 6.8 hours

Sample Standard deviation = 1.1 hours

Sample size = 38

Population standard deviation (Known, Not Known) = Not Known.

No. of tails = 2 (as we are calculating the confidence interval).

Since sample size is more than 30 use normal distribution.

Thus, we use z distribution.

a. Find the 90% confidence interval ...

#### Solution Summary

Computes the the 90% and 95% confidence interval for mean number of hours children watch television per day. Excel file is included.