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?
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 2 of 7.
Raghual R said:
6 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.
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.
(5)
Yudhisthira sarapuria said:
6 years ago
20% increase mean 120/100 = 6/5.
(4)
Ravi said:
6 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.
And answer will become 8:9.
And for girls:- 8+10/100.that is 81/10.
Then ATQ. 36/5*10/81.
And answer will become 8:9.
(2)
GANESH DEY said:
6 years ago
Please tell me, why denominator 5 is removed?
(4)
Abhishek chaturvedi said:
6 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.
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.
(1)
Siva said:
7 years ago
Can you say, how 42/5 : 44/5 = 21:22? Please explain clearly.
(4)
Aman said:
7 years ago
7 : 8 = 70 : 80.
70 * 120/100 = 84,
80 * 110/100 = 88,
So, 84:88 = 21:22.
70 * 120/100 = 84,
80 * 110/100 = 88,
So, 84:88 = 21:22.
(4)
Ruchith praharsha said:
7 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.
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.
(2)
Karthik Pangala said:
7 years ago
@Stark Vin.
We are taking X because ratio means dividing the total quantity into some parts and the number of parts we divide them into is represented in the form of the ratio.
For example, if I have 30 chocolates and if I want to divide them in the ratio 1:2 then first I will see into how many equal parts I need to divide the chocolates into that is 3 in this case why? Because ratio is 1:2 that is to parts I want is 3. That means I need to divide 30 into 3 equal parts and then take 1 part on one side and other part on the other side. This simply means if I divide 30 by 3 I get 10. This means I divided 30 into 3 equal parts where each part contains 10 chocolates. Now I need to divide them in the ratio 1:2 so I take 10 chocolate on one side which is one part of 30 in this example and remaining 2 parts which add up to 20 in other parts. Now 10 by 20 equals 1 by 2 or 1:2 that is what we call as ratio. That is ratio is the representation of total quantity in its simplest form. We could have written it as 10:20 by we need to simplify as much as possible so we take it as 1:2. Now coming to this question we have the boys to girls ratio as 7:8 that simply means the total strength was divide into 7+8 parts but since we do not know what is the total strength we take it as some variable say t now, t by 15 we assume as x. This means now I have divided total strength into 15 equal parts were each part contains x. In that 7x we take as number of boys and 8x as number of girls.
We are taking X because ratio means dividing the total quantity into some parts and the number of parts we divide them into is represented in the form of the ratio.
For example, if I have 30 chocolates and if I want to divide them in the ratio 1:2 then first I will see into how many equal parts I need to divide the chocolates into that is 3 in this case why? Because ratio is 1:2 that is to parts I want is 3. That means I need to divide 30 into 3 equal parts and then take 1 part on one side and other part on the other side. This simply means if I divide 30 by 3 I get 10. This means I divided 30 into 3 equal parts where each part contains 10 chocolates. Now I need to divide them in the ratio 1:2 so I take 10 chocolate on one side which is one part of 30 in this example and remaining 2 parts which add up to 20 in other parts. Now 10 by 20 equals 1 by 2 or 1:2 that is what we call as ratio. That is ratio is the representation of total quantity in its simplest form. We could have written it as 10:20 by we need to simplify as much as possible so we take it as 1:2. Now coming to this question we have the boys to girls ratio as 7:8 that simply means the total strength was divide into 7+8 parts but since we do not know what is the total strength we take it as some variable say t now, t by 15 we assume as x. This means now I have divided total strength into 15 equal parts were each part contains x. In that 7x we take as number of boys and 8x as number of girls.
Naresh said:
7 years ago
7*120/100 = 84/10,
8*110/100 = 88/10,
84/10:88/10 = 84:88.
21:22.
8*110/100 = 88/10,
84/10:88/10 = 84:88.
21:22.
(2)
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