Question

This week, over a span of six days, she ran a total of 38.4 miles. The distances, in miles, that Lisa ran throughout the week are as follows: 3.2, 7.5, 9.8, 11.5, 2.9, 3.5. What was the average distance of each run? Lisa's goal for this week is to run an average of 6 miles per day. How many miles does she need to run tomorrow (the 7th day) in order to achieve her goal of 6 miles per day for the week?

Answer 1

the average : 38.4 / 6 = 6.4 <==

(38.4 + x) / 7 = 6
38.4 + x = 7 * 6
38.4 + x = 42
x = 42 - 38.4
x = 3.6 <===she needs to run 3.6 miles