Word Problems: When to Use Mean, Median, and Mode

Tom's dad says he believes a $7$ year old boy will grow an average of $2$ inches from the time he turns $7$ to the time he turns $8.$ When they turn $7,$ the heights of 10 boys, in inches, are: $$45, 47, 44, 50, 44, 43, 49, 47, 40, 46$$

When they turn $8,$ their heights, in inches, are: $$48, 48, 45, 51, 49, 44, 52, 48, 43, 47$$ What is the difference in the average heights of the boys when they were $7$ versus when they were $8?$ Did the dad undershoot, overshoot, or guess correctly?