# Aptitude - Ratio and Proportion - Discussion

Discussion Forum : Ratio and Proportion - General Questions (Q.No. 12)
12.
If 40% of a number is equal to two-third of another number, what is the ratio of first number to the second number?
2 : 5
3 : 7
5 : 3
7 : 3
Explanation:

 Let 40% of A = 2 B 3

 Then, 40A = 2B 100 3

 2A = 2B 5 3

 A = 2 x 5 = 5 B 3 2 3

A : B = 5 : 3.

Discussion:
23 comments Page 1 of 3.

why are we not taking as 140 (40+100)in this case??

it is said 40% of a number
not increases by 40%
and the meaning 'of' is '*'

Why
2A/5=2B/3

A/B=2/3x5/2=5/3

Why not 2a/5=2b/3
then
2a*3=5*2b
6a=10b
=>A:B=3:5

Let A is FirstNumber
B is SecondNumber
40% of a number is equal to two-third of another number means
40%=40/100
40/100A=2/3B
a/b=40/100*2/3
a/b=3/5
a:b=3:5

Let the first number be 10. Its 40% is 4.

As in the question 40% of a number is two third of other.

Now we have to find that number and that is.

3\2 * 4 = 6.

For checking.

2\3 * 6 = 4.

And now 40 % meaning 4 lead it to full 100% meaning we get 10.

And know the ratio is.

10:6 or 5:3.

In these type of questions method is not must. Get some use of your natural machine.

If 40% of a number is equal to two-third of another number, what is the ratio of first number to the second number?

40% of x number is equal to 2/3.
So 40/100 =2/3.
If you get 200;120.
Simply 5:3.

Nivi said:   9 years ago
Why we took 40% of number 40/100 instead of 140/100?

Shrey said:   9 years ago
Ratio are given as 2:3:5.

200:300:500 (assume).

As 15% (230), 10% (330) and 20% (100) are respective increase in salaries.

New ratio 200:300:500.

230:330:600.

Kavitha said:   9 years ago
Please guide me through option testing for this sum.

Swagger said:   9 years ago
@Kusu you said why not 3:5:

Let say:

2A/5 = 2B/3.

First number being A and second number being B.

The question asked for the ratio of the first number to the second.

That means you got to get it into this form: A/B or A:B.

So rearrange 2A/5 = 2B/3 to get A/B = 5/3.

Therefore the ratio is of A:B is 5:3.