Ratio and Proportion

1.	The salaries A, B, C are in the ratio 2 : 3 : 5. If the increments of 15%, 10% and 20% are allowed respectively in their salaries, then what will be new ratio of their salaries?
	A. 3 : 3 : 10 B. 10 : 11 : 20 C. 23 : 33 : 60 D. Cannot be determined

Answer: Option C

Explanation:

Let A = 2k, B = 3k and C = 5k.

A's new salary =	115	of 2k =		115	x 2k		=	23k
	100			100				10

B's new salary =	110	of 3k =		110	x 3k		=	33k
	100			100				10

C's new salary =	120	of 5k =		120	x 5k		= 6k
	100			100

New ratio		23k	:	33k	: 6k		= 23 : 33 : 60
		10		10

2.	If 40% of a number is equal to two-third of another number, what is the ratio of first number to the second number?
	A. 2 : 5 B. 3 : 7 C. 5 : 3 D. 7 : 3 Answer: Option C Explanation: Let 40% of A = 2 B 3 Then, 40A = 2B 100 3 2A = 2B 5 3 A = 2 x 5 = 5 B 3 2 3  A : B = 5 : 3.

3.	The fourth proportional to 5, 8, 15 is:
	A. 18 B. 24 C. 19 D. 20 . Answer: Option B Explanation: Let the fourth proportional to 5, 8, 15 be x. Then, 5 : 8 : 15 : x  5x = (8 x 15) x = (8 x 15) = 24. 5

4.	Two number are in the ratio 3 : 5. If 9 is subtracted from each, the new numbers are in the ratio 12 : 23. The smaller number is:
	A. 27 B. 33 C. 49 D. 55 Answer: Option B Explanation: Let the numbers be 3x and 5x. Then, 3x - 9 = 12 5x - 9 23  23(3x - 9) = 12(5x - 9)  9x = 99  x = 11.  The smaller number = (3 x 11) = 33.

5.	In a bag, there are coins of 25 p, 10 p and 5 p in the ratio of 1 : 2 : 3. If there is Rs. 30 in all, how many 5 p coins are there?
	A. 50 B. 100 C. 150 D. 200 Answer: Option C Explanation: Let the number of 25 p, 10 p and 5 p coins be x, 2x, 3x respectively. Then, sum of their values = Rs. 25x + 10 x 2x + 5 x 3x = Rs. 60x 100 100 100 100 60x = 30     x = 30 x 100 = 50. 100 60 Hence, the number of 5 p coins = (3 x 50) = 150.