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Equations

Shruti inani (Student) (117 Points)

14 July 2018

Five year hence, the age of mukund will be three times that of his son. Five years ago, mukunds age was seven times that of his son. What are their present ages?

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14 Replies

Niranjan behera (nil) (43 Points)
Replied 14 July 2018

let, son age=X
then ,
mother age=3X

(3X+5)+5=2[(X+5)+10]
X=20=age of son
So, mother's age=60

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Shruti inani (Student) (117 Points)
Replied 14 July 2018

Sorry that's the wrong answer..

Niranjan behera (nil) (43 Points)
Replied 14 July 2018

let, son age=X
then ,
mother age=3X

(3X+5)+5=7[(X+5)+5]
X=15=age of son
So, mother's age=45

Shruti inani (Student) (117 Points)
Replied 14 July 2018

the answer is - son 10 mukund -40
even i got the same answer as yours but it is wrong unfortunately

Niranjan behera (nil) (43 Points)
Replied 14 July 2018

okay, next time
I will try to do correct

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Navghan Halvadia (Chartered accountant) (103 Points)
Replied 15 July 2018

Present age of son=x
Present age of father=Y
Y=(X+5)*3
Y=(X-5)*7
Y=3X+15
3X+15 = 7X-35
7x-3x = 15 + 35
4x = 50
X = 12.5
Y = 3X+15
= (12.5*3)+15
=52.5
Son=12.5
Father=52.5

Shruti inani (Student) (117 Points)
Replied 15 July 2018

i am afraid even this is the wrong answer.. the answer is son 10 years father 40 years. i dnt know how this came

Shivani Gupta (44 Points)
Replied 15 July 2018

Present age of father - x
Present age of son - y
Hence after 5 year age of father - x +5
And age of son -y + 5
Now, x+5=3(y+5)
=x-3y=10
Before 5 years,
Age of father was x-5
And age of son=y-5
Hence x-5=7(y-5)
=7y -x =30
Hence after solving both the equation
Ans will be
Father present age = 40
And son present age is 10
Hence the prove

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Shruti inani (Student) (117 Points)
Replied 15 July 2018

yes this is one method.. but i had doubt that why do we need to take x and y we can simply write the fathers age in terms of his son.. no need to take x and y only x but answer does not comes with it

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(Guest)

M + 5	=	(S + 5) X 3	M - 5	=	(S - 5) X 7
M + 5	=	3S + 15	M - 5	=	7S - 35
M	=	3S + 15 - 5	M	=	7S - 35 + 5
M	=	3S + 10	M	=	7S - 30


3S + 10	=	7S - 30
10 + 30	=	7S - 3S
40	=	4S
10	=	S
M	=	3 X 10 + 10
M	=	40

Shivani Gupta (44 Points)
Replied 15 July 2018

In this question there is no hint for father or son age computation and in present senerio we can not take both age in same manner because its impossible to have same age of father and son
Miss plzz try to understand the language of question we have only for future and past age that's why we have to let tham. And just becoz we have no hint for present age so we have to consider this separately

Navghan Halvadia (Chartered accountant) (103 Points)
Replied 15 July 2018

By taking only x ans will be the same but the solution will be lengthy
Son's present age = x
After 5 years father's age will be 3(x+5) = 3x+15
Hence present age of father = (3x+15)-5
Same in before 5 years father's age = 7(x-5) = 7x-35
Hence present age of father = (7x-35)+5
Now comparing both equation of present age
(3x+15)-5 = (7x-35)+5
3x+10 = 7x-30
4x = 40
X=10 age of son
Present age of father = 3x+15-5
45-5 = 40 age of father