Question

explain and show that 20,30,25,20 are in propotion or not?

Answer 1

Check whether the two ratios form a proportion or not:

(i) 6 : 8 and 12 : 16; (ii) 24 : 28 and 36 : 48

Solution:

(i) 6 : 8 and 12 : 16

6 : 8 = 6/8 = 3/4

12 : 16 = 12/16 = 3/4

Thus, the ratios 6 : 8 and 12 : 16 are equal.

Therefore, they form a proportion.

Answer 2

Answer:

20, 30, 25, 20 are not in proportion.

Step-by-step explanation:

=> 20,30,25,20 are in proportion or not?

>> 20 : 30 :: 25 : 20

Product of means = Product of extremes

=> 30 × 25 = 20 × 20

=> 750 ≠ 400

∴ 20, 30, 25, 20 are not in proportion.

Proportion:

An equality of two ratios is called a proportion. Four non-zero quantities a, b, c, d are said to be in proportion if a : b = c : d and we write as a : b :: c : d.

If a : b :: c : d, then:

1. a, b, c, are known as the first, second, third term respectively.
2. d is called the fourth proportional to a, b, c.
3. a and d are called extremes, while b and c are called means.

Product of extremes = Product of means:

If a : b :: c : d, then the product of means is equal to the product of extremes.

Proof: a : b :: c : d

=> a/b = c/d

=> ad = bc

∴ Product of extremes = Product of means