7. In an agricultural experiment to determine the e?ects of a particular insecticide, a field was planted with corn. Half the plants were sprayed with the insecticide, and half were unsprayed. Several weeks later, independent random samples of 200 sprayed plants and 200 unsprayed plants were examined. The number of healthy plants in each sample was as follows:
Sprayed Unsprayed
Healthy 131 111
Unhealthy 69 89
If the significance level is set at 0.05, does the evidence indicate that a higher proportion of sprayed than of unsprayed plants were healthy? Use a one tailed test (note - since the null is that the proportions are equal, use this information to construct a pooled estimate of the proportion).