Preocupado

09-20-2005, 02:37 AM

The problem below was on brazilian's last year Aeronautic Technology Institute's selection test.

Pure mathematics:

A mother is 21 years older than the son. In 6 months the mother's age will be 5 times superior to her son's age.

Question: Where is the father now?

You have to make some calculus to reach the answer and, as hard as it can be to believe, the answer will be given properly just by maths.

Scroll below for the solution.

Solution

Analizing today :

The mother is today Y years old

The boy is today X years old

If the mother is 21 years older: Y = X + 21

In 6 years from now: ( Y + 6 ) e ( X + 6 )

So with the mother five times older than the son : Y + 6 = 5 ( X + 6 )

Solving:

Y + 6 = 5 X + 30

Y = 5X + 24

Then, replacing on the first equation:Y = X + 21 We have:

5X + 24 = X + 21

Therefore:

- 4X = 3

X = -3/4

The boy has today -3/4 years, so, - 9 months (minus nine months!).

The answer is logical:

If the boy has exact minus 9 months, he will be born in 9 months, so:

Answer to the problem: The father is, right now, ejaculating.

Brilliant!

Pure mathematics:

A mother is 21 years older than the son. In 6 months the mother's age will be 5 times superior to her son's age.

Question: Where is the father now?

You have to make some calculus to reach the answer and, as hard as it can be to believe, the answer will be given properly just by maths.

Scroll below for the solution.

Solution

Analizing today :

The mother is today Y years old

The boy is today X years old

If the mother is 21 years older: Y = X + 21

In 6 years from now: ( Y + 6 ) e ( X + 6 )

So with the mother five times older than the son : Y + 6 = 5 ( X + 6 )

Solving:

Y + 6 = 5 X + 30

Y = 5X + 24

Then, replacing on the first equation:Y = X + 21 We have:

5X + 24 = X + 21

Therefore:

- 4X = 3

X = -3/4

The boy has today -3/4 years, so, - 9 months (minus nine months!).

The answer is logical:

If the boy has exact minus 9 months, he will be born in 9 months, so:

Answer to the problem: The father is, right now, ejaculating.

Brilliant!