A biologist wants to test whether chemically modifying a particular plant family will reduce their ability to retain water and moisture. In order to test this, a fixed volume of water is given to plants that have been chemically modified, and plants in a control group that have not been modified. The volume of moisture retained by each plant some time after is then recorded.

The statistics are given in the table below:

Volume of moisture retained
Group Sample Size Sample Mean (ml) Sample Standard Deviation (ml)
Control Group 24 146 114
Modified Group 23 106 115
At level of alpha = 0.05, the null hypothesis that chemical modification does not reduce the plant's ability to retain water and moisture is .