Question

When A = 20, B = 10. Also, when A = 5, B = 40. What can we say about A and B?

• A. They are directly proportional
• B. They are inversely proportional
• C. A+B = constant
• D. There exists no relation between A and B

Answer 1

The correct option is B

They are inversely proportional

First of all, when A increases, B decreases.
When A = 20, B =10.
So, AB = $20\times 10=200$
Also, when A = 5, B = 40.
Therefore, AB = $5\times 40=200$
Hence, we can conclude that $A\times B=200$ = a constant.
Thus, A and B are inversely proportional.