Question

Suppose the numbers A and B are directly proportional. Given that A = 6 when B = 14, what is the value of B if A = 9?

Answer 1

21

Explanation:

Old A: 6 New A: 9

Multiply 6 by 1.5 to get 9.

Therefore multiply 14 by 1.5 as well, which gives you 21.

Answer 2

21

Explanation:

The equation for direct proportion is

A = kB

We know A and B

6 = k (14)

Divide by 14

6/14 = 14k/14

3/7 = k

Rewriting

A = 3/7 B

Given A =9

9 = 3/7B

Multiply each side by 7/3 to isolate B

7/3 * 9 = 7/3 *3/7 B

21 = B