Samuel wants to know if kitchen compost improves the plant growth in his garden. He puts compost in the front half of his garden, but did not put it in the back half of his garden. Based on the data below, in inches, what can we say about the impact of the compost on the growth of plants in his garden?

Plant heights in the front half: 30, 29, 28, 14, 25, 35, 18, 22, 20, 12, 16, 17, 19, 10, 15

Plant heights in the back half: 26, 27, 19, 21, 20, 23, 9, 8, 14, 17, 18, 12, 10, 7, 6