Suppose that a particular type of plant has a median growing height of 20 inches in a specified time period when the best plant food currently on the market is used as directed. A developer of a new plant food wishes to show that the new plant food increases the median growing height. If a stem-and-leaf display indicates that the population of all growing heights using the new plant food is markedly nonnormal, it would be appropriate to use the sign test to test H0: Md = 20 versus H0: Md > 20. Here Md denotes the population median growing height when the new plant food is used. Suppose that 13 out of 15 sample plants grown using the new plant food reach a height of more than 20 inches. Test H0: Md = 20 versus Ha: Md > 20 by using the large sample sign test.