Q 8.14RP. - Elementary Statistics

Question

A random sample of size $25$ is taken from a population. A normal probability plot of the sample data shows three outliers but is otherwise roughly linear. Checking reveals that the outliers are due to recording errors and are really not outliers. The population standard deviation is known.

Step-by-Step Solution

Answer

It is clear that the distribution of the data is roughly linear. This indicated that the variable is normally distributed.

Step 1: Given information

A $25-$person random sample is chosen from a population. The sample data displays three outliers on a normal probability plot, but is generally linear.

Step 2: Concept

The formula used: is the $z-$interval procedure.

Step 3: Explanation

Check whether the z-interval process, the t-interval procedure, or neither is the best way for determining the confidence interval.

In this case, the z-interval algorithm should be performed to calculate the confidence interval.

• The standard deviation of the population is known.
• The normal probability plot clearly shows that the data distribution is essentially linear. This means the variable has a normal distribution.