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

A. 2.3 pounds
B. 2.8 pounds
C. 3.3 pounds



Answer :

To determine the weight of the fourth package, we follow these steps:

1. Calculate the total weight of all packages combined:
Given the mean (average) weight of the packages is 2.5 pounds and there are 4 packages, we first find the total weight of all the packages combined.
[tex]\[ \text{Total weight} = \text{Mean weight} \times \text{Number of packages} = 2.5 \times 4 = 10 \text{ pounds} \][/tex]

2. Sum the weights of the known packages:
We know the weights of three of the packages: 1.8 pounds, 3.2 pounds, and 2.7 pounds. We sum these weights to find the total weight of the known packages.
[tex]\[ \text{Sum of known weights} = 1.8 + 3.2 + 2.7 = 7.7 \text{ pounds} \][/tex]

3. Find the weight of the fourth package:
To find the weight of the fourth package, we subtract the sum of the weights of the known packages from the total weight of all packages combined.
[tex]\[ \text{Weight of the fourth package} = \text{Total weight} - \text{Sum of known weights} = 10 - 7.7 = 2.3 \text{ pounds} \][/tex]

4. Verify with the given options:
- 2.3
- 2.8
- 3.3

The weight of the fourth package is 2.3 pounds, which is one of the given options.

Thus, the weight of the fourth package is 2.3 pounds.