Suppose you have a data set that includes the values 2030 and 50 if you add a fourth value to this data set in after doing that the mean of the data set is 50 what was the value that you added?
a. -10
b. 40
c. 50
d. 100

D

Step-by-step explanation:

Without doing any math, you can deduce that in a data set with the values 20, 30, and 50, the only possible number you could add that could bring the mean (average) to 50 would be D or 100. But this method will not always work so instead I'll show how to do it mathematically:

(20 + 30 + 50 + x)/4 = 50

20 + 30 + 50 + x = 200

100 + x = 200

x = 100

step-by-step explanation:

you need a common difference between consecutive terms to be constant, like 1,2,3,4 or 2,4,6,8, or 1,3,6,9