Question

Mark (✓) against the correct answer:
x and y vary inversely. When x = 15, then y = 6. What will be the value of y when x = 9?
(a) 10
(b) 15
(c) 54
(d) 135

Answer 1

(a) 10

$x$	15	9
$y$	6	$y_1$

$$\begin{gathered} \mathrm{Since}x\mathrm{and}y\mathrm{var}y\mathrm{inversely},xy=\mathrm{constant}. \\ \mathrm{Now},15\times 6=9\times y_1 \\ \Rightarrow \frac{90}{9}=y_1 \\ \Rightarrow 10=y_1 \end{gathered}$$

∴ Value of y = 10, when x = 9.