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

Answer: Option A

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.

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