Question

what number should be added to each of the numbers 12,22,42 and 72 so that the resulting number may be in proportion

Answer 1

i hope the answer is 12.

Answer 2

Answer:

The required number added to each number is 3.

Step-by-step explanation:

To find : What number should be added to each of the numbers 12, 22, 42 and 72 so that the resulting number may be in proportion?

Solution :

Let the number be added is 'x'.

So, The required number formed is

12+x,22+x,42+x,72+x

Proportional of these numbers would be in this way.

$( 12 + x ): ( 22 + x ) :: ( 42 + x ) : ( 72 + x )$

or $\frac{(12+x)}{(22+x)}=\frac{(42+x)}{(72+x)}$

Cross multiply and solve,

$(12+x)\times (72+x)=(42+x)\times (22+x)$

$864+12x+72x+x^2=924+42x+22x+x^2$

$12x+72x-42x-22x=924-864$

$20x=60$

$x=\frac{60}{20}$

$x=3$

So, The required number added to each number is 3.

The numbers are

12+x=12+3=15

22+x=22+3=25

42+x+42+3=45

72+x=72+3=75