Question

$x$	$2$	$4$	$20$	$15$
$y$	$3$	$7$	$10$	$12$
$z$	$10$	$5$	$1$	$4/3$

Observe the table and find the quantities which are in inverse proportion

• A. $xandy$
• B. $xandz$
• C. $yandz$
• D. None of the above

Answer 1

The correct option is B $xandz$

By definition of inverse proportion,

$a\alpha \frac{1}{b}$ i.e. $a=K\frac{1}{b}$ $K=$ constant of proportionality

$\therefore a\times b=K$

From given example, consider

$x\times y=2\times 3\ne 4\times 7\ne 20\times 10\ne 15\times 12$

$x\times z=2\times 10=4\times 5=20\times 1=15\times \frac{4}{3}=20$

$\therefore$ $x$ and $z$ obey the equation $1$

Hence $x$ and $z$ are in inverse proportion.

Answer is B