Math question
Started by far123
For this kind of problems, I would just do backsolving. I would start with B.
The father's age is 24 NOW. Therefore the son must be 16 (b/c the ratio is 3:2)
So before 4 years father was 20 (24-4) & son was 12 (16-4). Now this ratio should be equal to 5:4, which it is. So the answer is B.
let f=fathers age, and s=sons age
we know
f/s=3/2
f=3s/2
we also know that
(f-4)/(s-4)=5/4
4(f-4)=5(s-4)
4f-16=5s-20
4f=5s-4
f=(5s-4)/4
Plug in first equation for f
3s/2=(5s-4)/4
6s/4=(5s-4)/4
6s=5s-4
s=-4
plug into f=3s/2
f=3(-4)/2
f=-6
The father's age is -6 🙂
Theres a prob with the question
we know
f/s=3/2
f=3s/2
we also know that
(f-4)/(s-4)=5/4
4(f-4)=5(s-4)
4f-16=5s-20
4f=5s-4
f=(5s-4)/4
Plug in first equation for f
3s/2=(5s-4)/4
6s/4=(5s-4)/4
6s=5s-4
s=-4
plug into f=3s/2
f=3(-4)/2
f=-6
The father's age is -6 🙂
Theres a prob with the question
you're right! I miscalculated the ratio at the end.
When you subtract the same number from numerator and denominator, the fraction you end up with should be GREATER than the original fraction (you need both to be positive though). In this case we go from 3/2 to 5/4 and obviously 3/2 > 5/4. You need it to be 5/3 to have a correct answer.
so he became a father at the age of 8? lol
Well it DOES say step son. Still kinda weird though.
