# Aptitude - Percentage - Discussion

### Discussion :: Percentage - General Questions (Q.No.6)

6.

If 20% of a = b, then b% of 20 is the same as:

 [A]. 4% of a [B]. 5% of a [C]. 20% of a [D]. None of these

Explanation:

 20% of a = b 20 a = b. 100

 b% of 20 = b x 20 = 20 a x 1 x 20 = 4 a = 4% of a. 100 100 100 100

 Indu said: (Aug 27, 2011) How (1/100)*20 comes?

 Arun . S said: (Sep 3, 2011) Here, 20% of a=b i.e.,(20/100)a=b then, b%20 i.e.,(b/100)*20---I then sub b=(20/100)a in I we get, =(20/100)a * (1/100) * 20 =(20/100)a * (20/100) =(400/10000)a =(4/100)a = 4% of a

 Habiba said: (Dec 7, 2011) A man bought a pen for #15 and later sold the pen for #60. What was the percent increase in the price of the pen?

 Cosmicguypradeep said: (Dec 11, 2011) @habiha here is the answer % increase = (actual increase/original price *100)% % decrease = (actual decrease/ original price *100)% so, for this question we have to calculate % increase (since the pen was sold at higher rate 45, which was actually bought for 15 Rs) (60-15/15 *100)% = 300%.

 Mahesh said: (Jan 15, 2012) In earlier sum, how =(20/100)a * (1/100) * 20 comes, because if we sub b=(20/100)a in I then that equ'n comes like ((20/100)a)/100*20 then how it comes (20/100)a * (1/100) * 20

 Kcs said: (Mar 21, 2012) Take a=100 b=20%a=20%100=20/100*100=20 b=20 20%b=20/100*20=4 4%a=4%100=4 5%a=5%100=5 20%a=20%100=20 ans=4%.

 Bharathi Prasath S said: (Jun 29, 2013) ((20/100*a=b) => a=5b). b/100*20=> b/5-->(1) 4% of a = 4/100*5b = b/5---> (2). (1) = (2). So option A.

 Rajeev said: (Nov 21, 2013) Actually I am unable to understand the explanation you have given. I think you are skipping some steps. Can anyone help me by giving proper answer with step by step.

 Anuj said: (Mar 12, 2014) Let assume a =100,then 20% of a=b. =20/100*100=> 20. That means b=20. Then b% of 20. b/100*20. It can also be written as (if we put the value of b). 20/100*20 =>4.

 Manish said: (Apr 8, 2014) 20/100*a = b. => a/5 = b. i.e. b = a/5. No b% of 20 is b/100 *20. = b/5. Replacing b with a/5. = a/25. = 0.04 a. = 4% of a.

 Alekya Reddy said: (May 7, 2014) If we take a = 20. 20%20 = 4. Therefore b = 4. Now 4%20 = 0.5. 20%a = b then b%20 is not equal to. Can you please clarify?

 Swaminathan Vembu said: (Jul 3, 2014) The Question -> f 20% of a = b, then b% of 20 is the same as ? Now since 20/100 * a = b, b = 1/5*a = 0.2a. b% of 20 implies 0.2a / 100 * 20 = 0.04a = 4% of a [4/100 * a].

 Agila said: (Jul 23, 2014) Please explain why a=20/100*a and b=b/100*20 why this different?

 Sunil said: (Aug 6, 2014) @Habiba simple step : 60-15 : 45. At present he bought it at 15 So, It is (45/15)*100: 300.

 Narayana Rao Gartam said: (Aug 7, 2014) Lets say A = 100, and B is 20% of A, So B = 20. Now, what 20% of B.( we need 20% from 20) i.e 4%.

 Uthaya Rani.S said: (Mar 16, 2015) 20/100*a = b. 20% of b = ? 20/100*b = 20a/100*20/100. (Because b = 20a/100, so 20b/100 = 400/1000). Answer = 4a/100 => 4%.

 Neha said: (May 11, 2015) 20% of a = b. Let a = 100. = 20/100*100 = 20. b = 20. = 20/100*20 = 4. 4% of a.

 Gurkirat said: (May 24, 2015) Good solutions all.

 Praveen said: (Jul 18, 2015) (20/100)*a equals b. a equals b*100/20. a equals 5 b. b equals a/5. Implies b equals 20 percentage of a.

 Balas said: (Dec 15, 2015) Any easy method?

 Naveen said: (Dec 16, 2015) 20 percentage of a = b. Then 20 percentage of b = ? b = 20 percentage of a. 20 percentage of b = 20 percentage of 20 percentage of a. = 20/100*20/100 of a = 4 percentage of a.

 Sanjit said: (Jun 19, 2016) What number is 60% less than 80? Please find and explain it.

 Soumya said: (Jul 18, 2016) @Sanjit. 80- 60 % (80), = 80- 60/100 * 80, = 80- 48, = 32.

 Rahulj said: (Aug 14, 2016) Nice explanation @Arun.

 Chakresh Patel said: (Aug 21, 2016) Nice @Arun, really it's very good explanation.

 Aditya said: (Sep 11, 2016) Let a =100 Now 20% of a i.e. 100 * 20/100 = 20 Rs. Means 100 Rs of a = 20 Rs of b. It means 1 Rs of a = 20/100 of b i.e 1/5 Rs. Now, 20% of 1/5 = 20 * 1/5 = 4 Rs.

 Sid said: (Sep 14, 2016) Why we put b as 1?

 Babar said: (Oct 27, 2016) Excellent @Neha.

 Kowsigan said: (Nov 24, 2016) Fresh grapes contain 80% water by weight and when the grapes are died, raisins contain 25% by weight. How many kgs of fresh grapes are needed to get 20kg of raisins? Please someone explain to solve this.

 Kiran Mali said: (Dec 9, 2016) 20% of a = b. Means, 20/100 * a = b. 0.2a = b. Means b = 0.2a, Now b % of 20 = suppose x, Means b/100*20 = x, But b = 0.2a, Meas 0.2a/100 * 20 = x 4a/100 = x. Means we get that's value x = 4% of a.

 Raj said: (Jan 4, 2017) 20% of a=b. 20 ÷ 100 of a = b. a = 5b. b = a ÷ 5. 1 ÷ 25 of a = (1 ÷ 25) * 100 of a = 4%.

 Hari said: (Jun 15, 2017) 20% of a = b, 20/100 of a = b, 0.2 of a =b, b% of 20. 0.2/100a * 20, 2/10 * 20a, 4%.

 Murugesh said: (Jun 23, 2017) Simple. a=b = 20% What is b% of 20, 20/100*20 = 4%.

 Ronalo said: (Jul 13, 2017) Thanks @Arun.

 Samarth Upalkar said: (Jul 22, 2017) 20% of a=(a/5)=b. b% of 20 = ((a/5)/100) * 20, = (a/500) * 20. = (4/100) * a, = 4% of a.

 Ram Mahes said: (Jul 27, 2017) Thank you so much @Kcs.

 Yash Chavan said: (Sep 11, 2017) Suppose a=100. then b=20%a, b=20/100*100 (a=100), b=20, Means if b=20. 20% of 20=20/100*20. = 4%.

 Leneri said: (Nov 21, 2017) If a=100 then 20% of a is b = 20. 20% of b =4. ( b% of 20 is the same as 20% of b). 4 out of 100 (4%).

 Sudarshan Prasad said: (Dec 22, 2017) Putting the value of b in b of 20% = 20% of a of 20% = 4/100 x a= 4% of a.

 Dieva said: (Jan 23, 2018) Agree @Sid. Why was b replaced with 1?

 Swapnil said: (Feb 13, 2018) (20% of a)/100 = (20% of a) * (1/100).

 Halvaraj said: (Jul 3, 2018) (20% of a)/100 = (20% of a) * (1/100).

 Sakshi said: (Aug 28, 2018) 20*20/100 = 400/ 100. = 4% is the answer.

 Narmadha said: (Aug 28, 2018) If you consider a=50, then the answer will not be 4%, there is no clue in the question that one should take a=100. When I assigned a=100 I got the answer as 4%, then when I assigned different value for a, the % varies.

 Ubaid Goje said: (Dec 10, 2018) Thanks @Swaminathan Vembu.

 Sagar said: (Dec 22, 2018) Hi, I am not understanding this. Anyone explain me to get the answer.

 Qadir said: (Jun 22, 2019) 20% of a = b --> Assume a as 100. So, 20% of 100 = 20 By this we can say b=20. Now, b% of 20 b=20% of 20=4 which is the answer.

 Prajwal said: (Jul 19, 2019) (20/100)a=b ----> (1) (b/100)*20=? --------> (2) So substitute (1) in (2). So we get [(20/100)/100]*20 ==>(4/100) ==>4% [because b=(20/100)a].

 Pavan said: (Aug 7, 2019) Anyone explain this.

 Sabari said: (Aug 29, 2019) 20% a = b when b is 20. a = (20/100)*20, a = 4.

 Prasad M said: (Sep 30, 2019) As percent always calculates at 100 ref. Let a= 100. 20% of a means - 20 which is b acc to question. 20 percent of again 20 (got above) is 4 percent of a. This doesn't require any paper calculations I believe, Hope it helps.

 Sriramamurthi said: (Jul 7, 2020) @All. 20% of a = b so in question they are given the b value. Then b% of 20 do now, Instead of b %, put the value of b, 20/100 of a*20 then cancel it properly. You will get the value of 4% of a. That will be our required answer.

 Sankar Nayak said: (Jul 26, 2021) If 20% of a=b means B =(20/100)*a ----> eq(1) And b%of 20 means (b/100)*20 ----> eq(2). If we put eq(1) value in eq(2) Then, [{(20/100)*a}/100]*100 If we simply fy it = {100/(100*20*a)}*20, => 1/(20*a)*20. => 1/a So ans is incorrect. If we modify qn and put 20% of b then (20/100)*b. We put b value i.e b = (20/100)*a, Then => (20/100)*(20/100)*a, If we simply fy it , then, (20*20/100*100)*a. And answer will be (4/100)*a. Means 4% of a.

 Varun said: (Aug 11, 2021) A = 100, B = 20. 20% of B = 2 * 2 = 4.

 Tenzin Tshedup said: (Aug 24, 2021) Let's say a = 100. 0.2 * 100 = 20 which is B, So, 0.2 * 20 = 4 which is equal to 0.04 * 100= 4.

 Sathish said: (Sep 29, 2021) Let's 20% is 1/5. 1/5 * 20 = 4.