13-15. At a garden center two types of fertilizers (call them A and B) are being tested. Sixteen identical plots are available for the test, with four seedlings planted in each plot. Fertilizer A is randomly applied to eight of the plots and Fertilizer B is applied to the remaining plots. After a month of consistent care the average height (in inches) of the four seedlings in each plot is calculated:

Fertilizer A Fertilizer B 12 11.2 13 10.8 12.8 14.2 13.8 12.7 11.5 13.1 12.4 10.1 10.6 15.1 14.9 12.9 For α = 0.05, is there any evidence that fertilizer B produces plants of greater height? Use the rank-sum test.