8. find the mean, median, mode and range of the data set after you perform the given operation on each data view. 13, 17, 15, 18, 21, 13, 20; add 3.7

a) mean: 20.4, median: 20.7, mode: 16.7, range: 8
b) mean: 16.7, median: 20.7, mode: 18.7, range: 8
c) mean: 21.7, median: 14.7, mode: 16.7, range: 8
d) mean: 16.7, median: 21.7, mode: 16.7, range: 8

13, 17, 15, 18, 21, 13, 20;(the add 3.7 has no place in this data set .Ignore it)

1) arrange the data from smaller to greater: 13 13 15 17 18 20 21

2) mean: Add up all data & divide by the number of data
     that is 7==> (117/)/7 so the mean = 16.71

3) Median is the central value of the data point that is in the middle of the sequence, so the median is 18

4) Mode the number that is most repeated & it's 13 (repeated twice)

5) The range is the difference between the largest & the smallest
Range = 21-13 ==> Range = 8

There is a problem in answers you have written: Either you mistyped or omitted something or the answer are false. With the data you gave me, my methodology is 100% right