Question

Fill in the boxes so that three numbers are in continued proportion. (a)25,20_

Answer 1

the first number =25
the second number=20
so the difference between first and second no. is 5
so the third no. = second no. - common difference
which = 15

Answer 2

If a, b, c are in continued proportion,

then a : b : : b : c

Let the unknown number be x.

So, 25, 20, x are in continued proportion.

25 : 20 : : 20 : x

For any proportion,

Product of means = Product of extremes.

Product of means = 20 * 20 = 400

Product of extremes = 25 * x = 25x

So,

⇒25x = 400

⇒ 25x = 25 * 16

⇒ x = 16.

Therefore, The unknown number is 16.

25, 20, 16 are in continued proportion.