Question

What is the "average atomic mass" of this set of pennies.

(can you guys also include a formula on how i can solve future problems like this, please.)

Answer 1

Answer:

A. 2.74g is the correct answer

Explanation:

Greetings!

$average \: mass = \frac{(mass \: pre - 1982 \times abundance) + (mass \: post - 1982 \times abundance}{100 } \\ ave = \frac{ (3.1g \times 40.0) + (2.5g \times 60.0)}{100} \\ ave = \frac{124 + 150}{100} \\ ave = \frac{274}{10} = 2.74g$

where, the sum of abundance always have to be 100%

Thus, 40.0 +60.0= 100.0