A researcher examined gross job gains and losses as a percentage of the average of previous and current employment figures. A simple random sample of 20 quarters provided the net percentage gains (losses are negative gains) for jobs as shown in the accompanying table. Complete parts (a) through (d) below.

a. Decide whether, on average, the net percentage gain for jobs exceeds 0.2 by using a hypothesis test with a 5% significance level. Assume a population standard deviation of 0.44.

b. Obtain a normal probability plot and a boxplot of the data.

c. Remove the outliers (if any) from the data and then repeat part (a).

d. Comment on the advisability of using the z-test for the original dataset.

Data set:

0.4 0.4 0.6 0.8 0.6 0.7 -0.3 -0.5 0.1 0.2

0.1 0.8 0.9 -0.2 -1.3 0.6 0.7 0.5 0.2 0.4