Directions: Study the following questions carefully and choose the right answer:
1
The total number of students in a school is 2140. If the number of girls in the school is 1200, then what is the respective ratio of the total number of boys to the total number of girls in the school?
» Explain it
B
Total No. of boys = 2140 – 1200 = 940 
 
Respective ratio = 940 : 1200 = 47 : 60.

Hence, option B is correct.
 
2
The income of A is 150% of the income of B and the income of C is 120% of the income of A. If the total income of A, B and C together is Rs. 86000, what is C’s income?
» Explain it
D
Let's take B's income as ₹ 100, then

A : B : C = 150 : 100 :  120 × 150
100

= 15 : 10 : 18

∴    C's share =  18 × 86000 = ₹ 36000
43

Hence, option D is correct.

3
Seats for Maths, English and General Knowledge are in the ratio of 5 : 7 : 8 respectively. There is a proposal to increase these seats by 40%, 50% and 75% respectively. What will be the respective ratio of increased seats ?
» Explain it
A
Required ratio = 5 ×  140  : 7 ×  150  : 8 ×  175
100 100 100

=  5 × 140 : 7 × 150 : 8 × 175  =  2 : 3 : 4

Hence, option A is correct.
4
48% of the first number is 60% of the second number. What is the ratio of the first number to the second number?
» Explain it
C
Let the first number be x and the second number be y

Then, 48% of x = 60% of y

or,   x  =  60%  =  5
y 48% 4

∴    Reqd ratio = 5 : 4.

Hence, option C is correct.

5
Shreya, Nikita and Kamini share the profit in the ratio of 7 : 8 : 9. They has partnered for 12 months, 9 months and 6 months respectively. What was the ratio of their investments?
» Explain it
A
Let the investment of Shreya be ₹ x,

that of Nikita be ₹ y and that of Kamini be ₹ z respectively.

Then, 12x : 9y : 6z = 7 : 8 : 9

or,    12x  =  7
9y 8

∴     32x = 21y

∴    21 y
32

And   9y  =  8
6z 9

∴    27y = 16z

∴    27 y
16

So, x : y : z =  21 : y  27 y  = 21 : 32 : 54
32 16

Hence, option A is correct.