Answer:
They need more than 2.5 inches.
Explanation:
average = 5.3
June: 6.3
July: 7.1
August: x
The average of the amounts for June, July, and August is
(6.3 + 7.1 + x)/3
To exceed the average, the average must be greater than 5.3.
(6.3 + 7.1 + x)/3 > 5.3
Multiply both sides by 3.
6.3 + 7.1 + x > 15.9
x + 13.4 > 15.9
Subtract 13.4 from both sides.
x > 2.5
Answer: They need more than 2.5 inches.