Ratio and Proportion Questions for Campus placement

Ratio and Proportion is an important topic for campus placement papers. It is also asked in TCS NQT, eLitmus as well as in competitive exams like CSAT, SSC, Banking, railways. Ratio and Proportion Basic concepts, formulas, short tricks and practice questions with solutions are given in this article.

Ratio and Proportion Formulas, short tricks, concepts

Ratio and Proportion

Ratio:  a and b are two quantities in the same units, then their ratio is given by a / b and we write it as a : b. Ratio shows the size of two quantities The multiplication or division of each term of a ratio by the same non-zero number does not affect the ratio. Eg. 2 : 3 = 4 : 6 = 6 : 9. Also, 4 : 6 = 2 : 3.

 Proportion: The equality of two ratios is called proportion.If a : b = c : d, we write a : b :: c : d and we say that a, b, c, d are in proportion.  a : b :: c : d 

Here a and d are called extremes, while b and c are called mean terms.

Product of means = Product of extremes.

 (b x c) = (a x d)

Fourth Proportional:   If a : b = c : d, then d is called the fourth proportional to a, b, c.

Third Proportional:  a : b = b : c, then c is called the third proportion to a and b.    

Mean Proportional:  if a:x :: x:b, then x is called mean proportion of a and b

Mean proportional between a and b is

x = (a  x b)^1/2

Ratio and Proportion Questions with Answers

Q.1 If A: B = 2 : 3 and B : C = 5 : 6 then what is the ratio of A : B : C ?
A) 2 : 3 : 5
B) 12 : 15 : 18
C) 10 : 15 : 18
D) 10: 12 : 18

Answer

multiply 5 in A : B and 3 in B : C so that the ratio term B becomes common 5 x 2 : 5 x 3 = 10 : 15
and 3 x 5 : 3 x 6 = 15 : 18
A : B = 10 : 15
B : C = 15 : 18
A : B : C = 10 : 15 : 18 ( ans)

Short trick : multiply as below

Answer 2 x 5 : 3 x 5 : 3 x 6
A:B:C = 10 : 15 : 18