SOLUTION: Mr John is 55years old. 15 years ago,he was 4 times older than his son.How old is his son now.

Question 1183017: Mr John is 55years old. 15 years ago,he was 4 times older than his son.How old is his son now.
Found 2 solutions by greenestamps, josgarithmetic:
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

The language used in the statement of the problem makes it impossible to know what the right answer is.

The phrase "4 times older than" should NEVER be used in the statement of a math problem.

If one person's age is x, then the correct interpretation of "4 times OLDER THAN x" is x, plus 4 more times x, or x+4x=5x.

On the other hand, if one person's age is x, then "4 times AS OLD AS x" would clearly be just 4x.

Unfortunately, sloppy use of everyday language nearly always has the two different phrases meaning the same thing.

So when the phrase is used in the statement of a math problem, we have no way of knowing which interpretation is correct. (But very probably the intended interpretation is the grammatically incorrect one.)

(1) The grammatically incorrect solution....

Let x be the son's age 15 years ago
Then 4x is John's age 15 years ago

John is 55 now, so 15 years ago his age was 40.
That means 15 years ago his son was 40/4=10.
And that means the son's age now is 10+15 = 25.

(2) The grammatically correct solution...

Let x be the son's age 15 years ago
Then x+4x=5x is John's age 15 years ago

John is 55 now, so 15 years ago his age was 40.
That means 15 years ago his son was 40/5=8.
And that means the son's age now is 8+15 = 23.

Very often is is possible to tell which interpretation is the intended one, because one interpretation will give a whole number answer and the other will not. And if that is the case, then nearly always the one that gives a whole number answer is the grammatically INCORRECT one -- which means the author of the problem is using sloppy language.

But in this problem, we can't tell which is the intended interpretation, because both give whole number answers.

Answer by josgarithmetic(39620) (Show Source): You can put this solution on YOUR website!
Mr. John today, 55
His son today, h
Mr. John fifteen years ago, 40
His son fifteen years ago, h-15

The description:

Simplify and solve,

RELATED QUESTIONS
3 years ago, John was 24 years older than his son. Now John is 5 times as old as his son. (answered by mananth)
3 year ago,john was 24 years older than his son. now john is 5 times old as his son. how... (answered by mananth)
three years ago john was 24 years older than his son now john is five time as old as his... (answered by mananth)
John is now 4 times older than his son, Ethan. Six years ago, the sum of their ages was... (answered by jorel1380)
John is 28 years older than his son. In two years he will be five times older than his... (answered by ewatrrr)
a father is 30 years older than his son. three years ago he was four times as old as his... (answered by richwmiller)
dr.kawasaki is twice as old as his son. twenty years ago, he was 4 times as old as his... (answered by mananth)
Mr. Jacobs is 4 times as old as his son. Five years ago, he was 9 times as old as his... (answered by w_parminder)
Dr. Nick is twice as old as his son. Twenty years ago, he was 4 times as old as his son... (answered by mananth)