An educational organization in California is interested in estimating the mean number of minutes per day that children between the age of 6 and 18 spend watching television per day. A previous study showed that the population standard deviation was 21.5 minutes. The organization selected a random sample of n = 200 children between the ages of 6 and 18 and recorded the number of minutes of TV that each person watched on a particular day. The mean time was 191.3 minutes. If the leaders of the organization wish to develop an interval estimate with 98 percent confidence, what critical value should be used?
A) z = 1.645
B) t = 2.38
C) Approximately z = 2.33
D) Can't be determined without knowing the margin of error.

Question

Quizplus · Accepted Answer

Since the population standard deviation is known and the sample size is large (n = 200), the appropriate distribution to use for constructing the confidence interval is the standard normal (Z) distribution. For a 98% confidence level, the critical value from the Z distribution is approximately 2.33.

An Educational Organization in California Is Interested in Estimating the Mean