Question

3. i) The ratio of ages of father and son is 7:2. After 5 years, the ratio of their ages will be 8:3.
Find the presentages of father and son.
ii) 2 women or 3 boys can finish a work in 48 hrs. In how many hours will 4 women and 6 boys
finish the work?
3x2=6

Answer 1

Answer:

let the present age of father is 7xyears

and the present age of son is 2x years

after 5 years

(7x+5) : (2x+5)=8 : 3

=> (7x+5)/(2x+5)=8/3

=> 8(2x+5)=3(7x+5)

=> 16x+40=21x+15

=> 16x-21x=15-40

=> -5x= -25

=> x= -25/-5

=> x=5

so present age of father is 7×5 years=35years

and present age of son is 2×5 years=10 years

Answer 2

Answer:

Let father age is 7x

And son age is 2x

then after 15 year father age is 7x+15

After 15 year son age is 2x+15

⇒  

2x+15

7x+15

​  

=  

1

2

​  

 

⇒4x+30=7x+15

⇒4x−7x=15−30

⇒−3x=−15⇒x=5

Hence father present age=7×5=35

Son present age=2×5=10

difference of father and son age=35−10=25

So father age was 25 years when son was born