Using proportions, it is found that $15.00 in quarters weigh 29.4 grams less today than before 1965.
A proportion is a fraction of a total amount.
In this problem, a quarter is worth $0.25, hence $15.00 in quarters is composed by 60 quarters, as:
[tex]\frac{15}{0.25} = 15 \times 4 = 60[/tex]
Before 1965, the total weight was of:
60 x 6.25 = 375 grams.
After that, the total weight is of:
60 x 5.76 = 345.6 grams.
Hence the difference is:
375 - 345.6 = 29.4.
$15.00 in quarters weigh 29.4 grams less today than before 1965.
More can be learned about proportions at https://brainly.com/question/24372153
