Can you explain how to calculate 15% and 20% trimmed mean of a given data set

3-16 The following data give the annual salaries (in thousand dollars) of 20 randomly selected health care workers. 50 71 57 39 45 64 38 53 35 62 74 40 67 44 77 61 58 55 64 59 a. Calculate the mean, median, and mode for these data. b. Calculate the 15% trimmed mean for these data