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
Solution:
(a) 10
Since $x$ and $y \operatorname{var} y$ inversely, $x y=$ constant.
Now, $15 \times 6=9 \times y_{1}$
$\Rightarrow \frac{90}{9}=y_{1}$
$\Rightarrow 10=y_{1}$
∴ Value of y = 10, when x = 9.