Aptitude - Problems on Ages - Discussion

Discussion Forum : Problems on Ages - General Questions (Q.No. 11)
11.
The present ages of three persons in proportions 4 : 7 : 9. Eight years ago, the sum of their ages was 56. Find their present ages (in years).
8, 20, 28
16, 28, 36
20, 35, 45
None of these
Answer: Option
Explanation:

Let their present ages be 4x, 7x and 9x years respectively.

Then, (4x - 8) + (7x - 8) + (9x - 8) = 56

20x = 80

x = 4.

Their present ages are 4x = 16 years, 7x = 28 years and 9x = 36 years respectively.

Discussion:
41 comments Page 4 of 5.

Ramya said:   9 years ago
It is simple method.

He has given present ages of persons mentioned that 8 years ago, then we can take as;
(4x - 8) + (7x - 8) + (9x - 8) = 56.

Lavanya said:   9 years ago
8 years ago sum of their age is 56,
Present sum of their age is 80
Total parts of the ratio is 4+7+9 = 20
So, 80/20=4
4 * 4 ,7 * 4, 9 * 4 = 16, 28, 36.

Pawan kumar said:   8 years ago
How to add 8?

Jon said:   8 years ago
I didn't understand.
First of all, from where 80 came.
Secondly, how do we know that we must plus, 4x-8 and 7x-8 how come there is + in between. Isn't it 8 years ago. Then why plus?

Please, someone, explain in very simple manner.

Tanweer said:   7 years ago
8 year ago total age 56.

Now 8x3=24+56=80 answer is B.
(1)

Tirth Patel said:   7 years ago
4 + 7 + 9 = 20x.

Eight years ago* three persons(8*3)=24.
Sum of their ages was= 56.
24+56=80x.
80/20=4.

Then 4:7:9 multiply by 4.
(4*4)=16,
(7*4)=28,
(9*4)=36.
The Answer is 16, 28, 36.
(4)

Krishan said:   6 years ago
8 years ago the sum of ages was 56.

At present, the sum of age will be 3*8+56 = 80.
(1)

Swathi hj said:   6 years ago
Can any one explain how that -8 comes.
(1)

Andrew said:   6 years ago
@Swathi,

-8 because the total is calculated for 8 years ago.
(1)

Krati said:   4 years ago
Thanks everyone.
(1)


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