We have that Jon's mean height is 62 in afters three checkups, and also we have that the first checkup was 58 in and the second checkup was 61 in. Then, the mean height will be the sum of the three checkups divided by the number of checkups:
where x is the third checkup. Then, we need to solve for x.
Then, the third checkup was 67 in. so, the answer is b.
In order for the average to be 62, the total of differences from 62 must be zero. The two given numbers have differences of -4 and -1, for a total of -5. In order for the total of differences to be zero, the third number must have a difference from 62 of +5. It must be 62+5 = 67.
Notice target point has y=0, so all terms with y are zero. Then all 6 equations reduce to m x = k, for various m and k. So calculate 4×m and compare to k six times.
