I can't figure out the degree of freedom.

The Journal de Botanique reported that the mean height of Begonias grown while being treated with a particular nutrient is 40 centimeters. To check whether this is still accurate, heights are measured for a random sample of 14 Begonias grown while being treated with the nutrient. The sample mean and sample standard deviation of those height measurements are 47 centimeters and 12 centimeters, respectively. Assume that the heights of treated Begonias are approximately normally distributed. Based on the sample, can it be concluded that the population mean height of treated begonias, JI, is different from that reported in the journal? Use the 0.10 level of significance. Perform a two-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places. (If necessary, consult a list of formulas.) (a) State the null hypothesis Ho and the alternative hypothesis H,. H : H = 40 1X H, : 1 = 40 (b) Determine the type of test statistic to use. -0 030 020 Degrees of freedom: www.youtube.com . 5m