Question

Seventh graders collected some gold sand on a class field trip.

Class 7A collected 40 oz of gold sand that contains 12% gold.
Class 7B collected 55 oz of gold sand that contains 11% gold.
How much pure gold did 7A collect?

Answer 1

Class 7A collected 4.8 ounces of pure gold.

Explanation:

Key skills required are: Percentages, Multiplication

1. We only need the information about Class 7A. They collected 40 oz that contains 12% gold.
2. In other words, this means that 12% of that 40 oz gold sand is pure gold.

Here we have to do 12% x 40 to find the number of oz of pure gold. We first have to convert 12% into a decimal. Divide it by a 100 (or move the decimal point 2 places to the left) and you will get 0.12.

Do 0.12 x 40 and you will get 4.8

Therefore, there are 4.8 oz of pure gold in Class 7A's gold sand