Frank wanted to see whether adding some compost to the soil would affect the size of the vegetables in his garden. He created two pumpkin patches with similar sun exposure. In one patch, Frank used only the natural soil in his garden, and in the other patch, he mixed some compost in with the natural soil. He then sowed the same type of pumpkin seeds in both patches, and watered them on identical schedules. When the pumpkins were ready to harvest, Frank measured the approximate diameters, in inches, of the pumpkins in each patch. The summary statistics are shown in the table. What is a 90% confidence interval for the difference between the mean diameters of the pumpkins in each patch? (You may assume that there are = 30 degrees of freedom.)
A) (3.83, 8.17)
B) (4.20, 7.80)
C) (4.61, 7.39)
D) (4.73, 7.27)