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
Answer: Option
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:
25 comments Page 3 of 3.

Talha said:   1 decade ago
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.

Jisha said:   1 decade ago
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

Kusu said:   1 decade ago
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

Aparna said:   1 decade ago
hey,read the question carefully
it is said 40% of a number
not increases by 40%
and the meaning 'of' is '*'

Raghu said:   1 decade ago
why are we not taking as 140 (40+100)in this case??


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