Aptitude - Problems on Ages - Discussion
Discussion Forum : Problems on Ages - General Questions (Q.No. 13)
13.
A person's present age is two-fifth of the age of his mother. After 8 years, he will be one-half of the age of his mother. How old is the mother at present?
Answer: Option
Explanation:
Let the mother's present age be x years.
| Then, the person's present age = |  |
2 | x |  |
years. |
| 5 |
 |
|
2 | x + 8 | |
= | 1 | (x + 8) |
| 5 | 2 |
2(2x + 40) = 5(x + 8)
x = 40.
Discussion:
59 comments Page 2 of 6.
Yoga said:
1 decade ago
Thanks Yuga!...
Nithi said:
1 decade ago
Hai friends! please give one clear solution for that question.
Vijay said:
1 decade ago
Hey but does x=40 means after 8 years. They have asked for present age. Doesn't it should be x=32, the present age ?
Varun said:
1 decade ago
Vijay, I was wondering about the same I think your right.. :)
The ans should be 40-8-32 present age of person's mother.
The ans should be 40-8-32 present age of person's mother.
Vivek said:
1 decade ago
One-half is 3/2 and not 1/2 and the x denotes the current age! so by what they have solved, 40 is right!! but one half is 3/2 and definitely not 1/2!
Sam said:
1 decade ago
As far as I can see in the third step they have taken the LCM on Left hand side but didn't do that on the right hand side. Just wondering if I am right. And if that's the case why didn't they do the same on RHS (right hand side) ?
Akshitha said:
1 decade ago
ONE HALF is the irreducible fraction resulting from dividing one by two (½), or any number by its double; multiplication by one half is equivalent to division by two. It appears often in mathematical equations, recipes, measurements, etc. Half can also be said to be one part of something divided into two equal parts.
Shravya said:
1 decade ago
@Yuga how you simplified it can you please explain it. Your method is good but please can you tell how you calculated it.
Nagarjuna.N said:
1 decade ago
Let Mother Present age = x
Person age = (2/5)x
After 8 Years Persons Age Will be = (2/5)x + 8
After 8 Years Mother Age Will Be x + 8
Given That After 8 years, Person will be one-half of the age of his mother.
Here One-Half Means 3/2 actually . (But He Take 1/2 in the Explanation . So let we take 1/2).
(2/5)x + 8 = (1/2)(x+8).
(2x + 40)/5 = (x+8)/2.
4x + 80 = 5x + 40.
x = 40.
Mother Present Age x = 40.
Person age = (2/5)x
After 8 Years Persons Age Will be = (2/5)x + 8
After 8 Years Mother Age Will Be x + 8
Given That After 8 years, Person will be one-half of the age of his mother.
Here One-Half Means 3/2 actually . (But He Take 1/2 in the Explanation . So let we take 1/2).
(2/5)x + 8 = (1/2)(x+8).
(2x + 40)/5 = (x+8)/2.
4x + 80 = 5x + 40.
x = 40.
Mother Present Age x = 40.
Cynthia said:
1 decade ago
Please I need explanation on solving this equation:
2/5x+8 = 1/2(x+8).
Are we not meant to cross multiply. I don't understand how you came about the 40?
2/5x+8 = 1/2(x+8).
Are we not meant to cross multiply. I don't understand how you came about the 40?
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