Math word problem

Question

Yellows vary inversely as reds cubed. When there are 16 yellows, there are 4 reds. How many yellows are present when there are 8 reds?

Answer 1

Let y be the yellows and x be the reds.

y = k/x³

When y=16 and 4 reds: 16=k/4³ --> k = 16(4)³

y = 16(4/x)³

When x = 8, y = 16(4/8)³=16(1/2)³=16/8= 2

There are 2 yellows.