Question

Which of the following is/are in inverse proportion?

• A.

  x	5	7	9
  y	6	5	4

• B.

  x	8	12	24
  y	6	4	2

• C.

  x	30	15	10
  y	3	6	9

• D.

  x	32	16	12
  y	4	8	10

Answer 1

Answer: (B), (C)

The correct options are
B

x	8	12	24
y	6	4	2

C

x	30	15	10
y	3	6	9

We know that, for two variables $x$ and $y$ to be in inverse proportion,
$x\times y=constant$

$\left(i\right)$
$5\times 6=30$
$7\times 5=35$
$9\times 4=36$
Sine, $x\times y\ne constant$,
they are not in inverse proportion.

$\left(ii\right)$
$8\times 6=48$
$12\times 4=48$
$24\times 2=48$
Sine, $x\times y=constant$,
they are in inverse proportion.

$\left(iii\right)$
$30\times 3=90$
$15\times 6=90$
$10\times 9=90$
Sine, $x\times y=constant$,
they are in inverse proportion.

$\left(iv\right)$
$32\times 4=128$
$16\times 8=128$
$12\times 10=120$
Sine, $x\times y\ne constant$,
they are not in inverse proportion.