To calculate the average value of a given set, you have to add all observations and divide it by the number of components of said set.
Using the formula

∑x: represents the sum of observations
n= total number of components in the set.
For the first set you have three different observations of three different flights, the average for this set is:

The average distance was 9.67feet
For the second set, you have three observations:

The average distance was 4.67feet
Since theThe airplane flew on average a greater distance in the first time than in the second time.