Question

A jar containing 140 marbles weighs 20 ounces, and the same jar containing only 100 marbles weighs 16 ounces. What is the weight of the jar?

Answer 1

You should first calculate the weight of each marble

20 - 16 = 4 ounces difference between the 2 jars
140 - 100 = 40 marble difference between 2 jars

4 ounces divided by 40

4 ÷ 40 = 0.1 ounces per marble

So each marble is .1 ounces

0.1 ounces times 100 marbles (in second jar)

0.1 × 100 = 10 ounces of marbles

Jar + 10 ounces = 16 ounces

Jar = 16 - 10

Jar = 6 Ounces