### Discussion :: Ratio and Proportion - General Questions (Q.No.6)

K.Kiran Kumar said: (Aug 4, 2010) | |

I can not get that how 120% of 7x and 110% of 8x. Please someone explain it. |

Ramesh said: (Dec 9, 2010) | |

7:8 can also be written as 70:80 120/100*70 = 84 110/100*80 = 88 so,new ratio= 84 : 88 or 42 : 44 or 21 : 22 |

Abhinesh said: (Jan 12, 2011) | |

(7x+0.2*7x)/(8x+0.1*8x)=21:22 |

Sripal S said: (Mar 6, 2011) | |

@Kiran Kumar note that something we included to get 20% For example the ratio of the ratio of to boys ages was 5:2 we can write it as 5x : 2x we get exact ratio we will not consider it alone For that way 7x 8x will appear then to covert 20% into no. it will be 20/100 note that the unknown was x then 20/100x*x so we take common one x(20/100+1) so x(20/100+100) x(120/100) that was we get 120/100 forget x because that x which is in 7x both are same so we get 120/100*7x |

Sasha said: (May 6, 2011) | |

I like ramesh's methods ! thanks a lot :). |

Poonma said: (Jun 14, 2011) | |

Ramesh your to good. |

Khushboo said: (Jul 19, 2011) | |

Why do we multiply 120% by 7x and 100% by 8x Why not we simply multiply 20% by 7x and 10% by 8x ? Please someone explain me. |

Raj said: (Aug 9, 2011) | |

RAMESH very well said. ! keep posting your SHORTCUT method. Its very useful for us. !i search at every discussion. Because of you. ! |

Priyabrata said: (Sep 26, 2011) | |

20% of 7=14/10,total increase 7+14/10=84/10 10% of 8=8/10,total increase 8+8/10=88/10 now compare ratio of Boys and Girls 84/10:88/10 or 84:88 or 42:44 or 21:22 |

Kavya said: (Sep 29, 2011) | |

I am getting 7:4 by whichever method I do. I am not satisfied with any explanations given. Help me. |

Rajeev said: (Nov 8, 2011) | |

@ ramesh Can you tell you multiply 70 & 80 instead of 7 & 8, as we get same answer in both the cases? |

Prasanna said: (Jan 9, 2012) | |

@rajeev. Yes you get the same answers. |

Sunali said: (Feb 22, 2012) | |

Thanks priyabhrt. |

Pankaj said: (Jul 31, 2012) | |

There is some problem to understand the problem ie question is asked 20% and 10% but here get 120% and 110% why ? |

Zahir said: (Oct 8, 2012) | |

20%of7 = 7/5 that means boys total = 7+7/5. =42/5. 10%of8 = 4/5 that means girls total = 8+4/5 = 44/5. Boys : Girls = 42/5:44/5. =42:44. =21:22. |

Nive said: (Aug 9, 2013) | |

Simply find 20% of 7 and 10% of 8. It will be 1.4 and 0.8 respectively. So the ratio is 8.4:8.8. Then convert the fraction into whole numbers. If I multiply by 10 I will get 84:88 now we can easily simplify it. So we get 21:22. |

Gowtham said: (Dec 11, 2013) | |

Simply find 20% of 7 and 10% of 8. It will be 1.4 and 0.8 respectively. Till this ok then,how 8.4:8.8. And how to convert it into fraction. So the ratio is 8.4:8.8. Then convert the fraction into whole numbers. If I multiply by 10 I will get 84:88 now we can easily simplify it. So we get 21:22. |

Stark Vin said: (Apr 15, 2014) | |

Hi all, One minor doubt, why we are using for every question for ratio, what x mean? is a assumed value or what ? for this question if we didn't use x also we are getting the answer, but in other cases, we need to use X, please suggest me a good method. Thanks. |

Atul1487 said: (Apr 26, 2014) | |

Boys: Girls. 7:8. 20% increase in boys no. so, 7*20% = 1.4 so total boys = 7+1.4 = 8.4. 10% increase in girls. 8*10% = 0.8 So total Girls = 8+0.8 = 8.8. So Ratio of Boys & Girls. 8.4 : 8.8. 21:22 Answer. |

Md Shahrukh said: (May 24, 2014) | |

Let the no of boys 7 and girls 8. 7x120/100: 8x110/100. 840:880. So answer is 21:22. |

Narayana Rao Gartam said: (Aug 18, 2014) | |

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: (Aug 30, 2014) | |

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: (Nov 25, 2014) | |

Can someone give short method? |

Mateen said: (Feb 1, 2015) | |

How 120 and 110 come into the picture? Please explain sir. |

Arvind_Ap said: (Mar 29, 2015) | |

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: (Apr 6, 2015) | |

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: (Apr 25, 2015) | |

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: (Jul 22, 2015) | |

How you took ratio 21:22 from 42/5:44/5? How 5 is eliminated please explain? |

Prakash said: (Aug 12, 2015) | |

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. |

Swastik said: (May 1, 2016) | |

Thanks @Priyabrata. Your method is easy to solve the problem. |

Moorthi said: (Aug 17, 2016) | |

How you took ratio 21:22 from 42/5 : 44/5? How 5 is eliminated? Please explain. |

Rosy said: (Sep 11, 2016) | |

42/5 and 44/5 how is it 21 : 22? Please explain in detail. |

Riya said: (Sep 19, 2016) | |

The ratio of the cost price and selling price is 4:5 what is the profit percentage? Does anyone know how to solve this? |

Ajay said: (Oct 11, 2016) | |

7 * 20/100 = 7/5, 7/5 + 7 = 42/5, 8 * 10/100 = 4/5, 4/5 + 8 = 44/5, 42/5 : 44/5 = 21 : 22. |

Mohanraj said: (Oct 12, 2016) | |

The first ratio is 7 increase proposal is 120 (100% + 20%). The second ratio is 8 increase proposal is 110 (100 + 10%). The ratio is 7 * 120 = 840 : 8 * 110 = 880. The answer of the new ratio is 21 : 22. |

Chaitra said: (Dec 4, 2016) | |

Ramesh sir, how you get 42:44? |

Muhammad Naeem said: (Dec 17, 2016) | |

@Chaitra. 6 * 7 = 42 and 11 * 4 = 44. |

Yamini Saraswathi said: (Feb 8, 2018) | |

Actually, I am getting answer as a (120/100)*7=8.4 so approximately = 8. (110/100)*8=8.8 so approximately = 9. The answer is 8:9. |

Abhishek Bansal said: (Feb 11, 2018) | |

Given : B : G = 7:8. This can be written as 7x : 8x ( X being the common multiplier). Let x = 10 (For simple Calculation) So Boys = 70 & Girls = 80. Increased Of Boys by 20% = 70*20/100 = 14. So After Increase boys would be = 70 + 14 = 84. Similarly Girls = 80*10/100 = 8 & Girls After Increase would be = 80 + 8 = 88. New Boys : New Girls = 84:88. Simply 21:22. |

Pawan said: (Mar 8, 2018) | |

7+8=15. %= 15+100=150, 7:8 increase by 20% & 10%, 70= 20%=14, 80=10%=8, Therefore, 70+14=84, 80+8=88, 84:88, Divide by 4, Hence new ratio is; 21:22. |

Charan said: (Mar 23, 2018) | |

The total percent of 7x is 100% and they increase 20% so we take it as 120*7x in the same way 110*8x is taken. |

Naresh said: (May 28, 2018) | |

7*120/100 = 84/10, 8*110/100 = 88/10, 84/10:88/10 = 84:88. 21:22. |

Karthik Pangala said: (Jul 28, 2018) | |

@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. |

Ruchith Praharsha said: (Sep 12, 2018) | |

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. |

Aman said: (Jan 10, 2019) | |

7 : 8 = 70 : 80. 70 * 120/100 = 84, 80 * 110/100 = 88, So, 84:88 = 21:22. |

Siva said: (Feb 8, 2019) | |

Can you say, how 42/5 : 44/5 = 21:22? Please explain clearly. |

Abhishek Chaturvedi said: (Sep 10, 2019) | |

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. |

Ganesh Dey said: (Sep 19, 2019) | |

Please tell me, why denominator 5 is removed? |

Ravi said: (Sep 30, 2019) | |

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. |

Yudhisthira Sarapuria said: (Oct 27, 2019) | |

20% increase mean 120/100 = 6/5. |

Raghual R said: (Dec 27, 2019) | |

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. |

Sam said: (May 30, 2020) | |

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. |

Waquar said: (Aug 11, 2020) | |

Thanks @Priyabrata. |

#### Post your comments here:

Name *:

Email : (optional)

» Your comments will be displayed only after manual approval.