A researcher is investigating whether a difference exists in the mean weight of green-striped watermelons grown on two different farms: one that uses organic methods and one that uses nonorganic methods. The mean and standard deviation of the weights in a random sample of 43 watermelons from the organic farm were 18 pounds and 2 pounds, respectively. The mean and standard deviation of the weights in a random sample of 40 watermelons from the nonorganic farm were 20 pounds and 1.7 pounds, respectively. Required:
What represents the standard error of the difference in the mean weights of watermelons from the two farms?