Question

A metallurgist wants to make 130 grams of an alloy that is to be 20% copper. She has samples that are 14% copper and 22% copper. How many grams of the sample that contains 14% should she use?

Answer 1

She should use 32.5 g of the sample that contains 14%

Explanation:

Here, we want to know the number of grams of the sample that contains 14% copper that should be used

let the number of grams that contains 14% copper to be used be x

Then the number of grams of 22% will be 130-x

Thus, mathematically;

0.14(x) + 0.22(130-x) = 0.2(130)

0.14x + 28.6 - 0.22x = 26

0.22x - 0.14x = 28.6 - 26

0.08x = 2.6

x = 26/0.08

x = 32.5