Question

$$\begin{array}{ccccc}X& 100& 200& 300& 400\\ Y& & 30& 20& 15\end{array}$$

What is the value of $y$ when $x$ = 100

• A. 60
• B. 70
• C. 80
• D. 90

Answer 1

The correct option is A

60

From the table , we can observe as x increases, y decreases

Hence x is inversely proportional to y

$\therefore$ $xy$ = constant

$\therefore$ if x = 100 and y = 30 , then $x\times y$ = $200\times 30$ = 6000 = constant

$\therefore$ if x = 100 , then y = $\frac{6000}{100}$ = 60