Sure, let's break down the solution step-by-step.
1. Identify Given Data:
- Number of pre-1982 pennies: 8
- Average mass of pre-1982 pennies: 3.1 grams
- Number of post-1982 pennies: 12
- Average mass of post-1982 pennies: 2.5 grams
2. Determine What is Asked:
We are asked for the total mass contributed by the post-1982 pennies.
3. Calculate Total Mass of Post-1982 Pennies:
To find the total mass contributed by the post-1982 pennies, we need to multiply the number of post-1982 pennies by their average mass:
[tex]\[
\text{Total mass of post-1982 pennies} = \text{number of post-1982 pennies} \times \text{average mass of post-1982 pennies}
\][/tex]
4. Perform the Calculation:
[tex]\[
\text{Total mass of post-1982 pennies} = 12 \times 2.5
\][/tex]
5. Compute the Result:
[tex]\[
\text{Total mass of post-1982 pennies} = 30.0 \text{ grams}
\][/tex]
Thus, the post-1982 pennies contribute a total mass of 30.0 grams to the weighted average mass.
