Question

The mean weight of the packages Joan shipped was 2.5 pounds. If Joan mailed four packages and three of them had weights of 1.8, 3.2 and 2.7 pounds, then what did the other package weigh?

Answer 1

2.3 pounds

Explanation:

First, the mean is equal to the sum divided by the number of numbers.

There are four packages, so there are four numbers. Let's say the fourth package has a weight of x. We can then write

mean = sum / number of numbers

2.5 = (1.8+3.2+2.7+x)/4

multiply both sides by 4 to remove the denominator

10 = 1.8+3.2+2.7+x

10 = 7.7 + x

subtract 7.7 from both sides to isolate the x

x = 2.3 pounds