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
Answer: Option
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:
61 comments Page 6 of 7.

Md shahrukh said:   1 decade ago
Let the no of boys 7 and girls 8.

7x120/100: 8x110/100.

840:880.

So answer is 21:22.

Narayana Rao Gartam said:   1 decade ago
20% of 70 is 14 (20/100*70) So, Total increase is 84.
10% of 80 is 8 So, total increase is 88.

Ratio of 84/88 = 21/22,
i.e 21:22.

Prakash yadav said:   1 decade ago
20%of 7 = 1.4 : 10%of 8 = 0.8 .
7+1.4 : 8+0.8;

8.4 : 8.8;
84/10 : 88/10;

42/5 : 44/5;
21 : 22.

Simran said:   1 decade ago
Can someone give short method?

Mateen said:   1 decade ago
How 120 and 110 come into the picture? Please explain sir.

Arvind_ap said:   1 decade ago
G, B.

7:8 = 70, 80.

20% 10% = 120, 110.

G = 70*120 = 840.

B = 80*110 = 880.

= 84/88 = 21/22.

Answer = 21:22.

Ankita said:   1 decade ago
Why we use decimal values instead of fraction value?

20% of 7 = 7/5.
10% of 8 = 4/5.
7/5:4/5 = 7:4.

So answer should be 7+7:4+8 = 14:12.

Aditya said:   1 decade ago
We also 7:8 is 70:80.

So 20% and 10% =120 and 110.

Then 70*120 = 840, 110*8 = 880.

Simply divide them, 840/880 = 21/22 (Answer).

Hackersk said:   1 decade ago
How you took ratio 21:22 from 42/5:44/5?

How 5 is eliminated please explain?

Prakash said:   1 decade ago
Please tell me easy steps or tricks to find ratios in complex cases without working a lot of steps!

I m waiting! for your reply.


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