An average lawn has a mean of 21 blades of grass per square inch. A garden store sells an expensive fertilizer designed to transform an average lawn into a lush, thick carpet within three weeks. To test the claim, a random sample of an average lawn plot was obtained. Each was treated with fertilizer according to the instructions on the package. Three weeks later the density of each plot was measured by counting the blade of grass per square inch. The summary statistics were n=32, sample mean = 22.4, and sample standard deviation = 2.7. Researchers want to determine if the fertilizer improves the thickness of an average lawn.

1. What is the test statistics of the hypothesis test?

3.90

1.57

2.93

0.52

4.82

2. What's your decision for the hypothesis test at a 5% significance level?

We fail to reject the null and support the alternative.

We reject the null and support the alternative.