# Aptitude - Ratio and Proportion - Discussion

Discussion Forum : Ratio and Proportion - General Questions (Q.No. 6)
6.
The ratio of the number of boys and girls in a college is 7 : 8. If the percentage increase in the number of boys and girls be 20% and 10% respectively, what will be the new ratio?
8 : 9
17 : 18
21 : 22
Cannot be determined
Explanation:

Originally, let the number of boys and girls in the college be 7x and 8x respectively.

Their increased number is (120% of 7x) and (110% of 8x).  120 x 7x and 110 x 8x 100 100 42x and 44x 5 5 The required ratio = 42x : 44x = 21 : 22. 5 5

Discussion:
53 comments Page 1 of 6.

Waquar said:   3 years ago
Thanks @Priyabrata.

Sam said:   3 years ago
Given 7:8.

They said there is 20% and 10% increase in this ratio
Which means with this 7 , there is 20% increase of 7 .similarly for 8
That is;

7 + 7 * 20/100 : 8+8*10/100.
7+ 7/5 : 8+4/5,
21:22.
(1)

Raghual R said:   3 years ago
We can write 7:8 as 7x and 8x . If x = 1000.
Then 7000 : 8000.
20% of 7000 = 1400 then total boys = 7000+1400 = 8400;
10% of 8000 = 800 then total girls = 8800.
So the new ratio is 8400:8800 which is 21:22.
(1)

Yudhisthira sarapuria said:   3 years ago
20% increase mean 120/100 = 6/5.
(1)

Ravi said:   3 years ago
For boys :- 7+20/100. that is 36/5.

And for girls:- 8+10/100.that is 81/10.

Then ATQ. 36/5*10/81.

(1)

GANESH DEY said:   4 years ago
Please tell me, why denominator 5 is removed?

Abhishek chaturvedi said:   4 years ago
Let the boys be 7x and girls be 8x.

Boys 20 percent = 7x * 20/100 = 7X/5.
Girls 10 percent = 8x * 10/100 = 4x/5.
Total boys = 7X + 7x/5 = 42x/5.
Total girls = 8x+ 4x/5 = 44x/5.

So, ratio;

Total boys : total girls = 42x/5 /44x/5 = 22/22 = 21:22.

Siva said:   4 years ago
Can you say, how 42/5 : 44/5 = 21:22? Please explain clearly.

Aman said:   4 years ago
7 : 8 = 70 : 80.
70 * 120/100 = 84,
80 * 110/100 = 88,

So, 84:88 = 21:22.
(1)

Ruchith praharsha said:   5 years ago
Let the no of boys be 7x and no of girls be 8x.

If it is increased by 20 and 10 per cent lets take x as 10 they will 70 and 80 and the increase will be 84 and 88 the ratio is 84 :88 that is 21:22.