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How Old is Malcolm, His Dad and Grandfather?

Malcolm is the number of weeks of his father’s age treated as days and his grandfather’s age in months. All three of their ages add up to 120 years. How old is Malcolm, his father and his grandfather?

Malcolm is 6.
The father is 42. 42 days = 6 weeks.
The grandfather is 72. 72 months = 6 years.


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6 Comments on "How Old is Malcolm, His Dad and Grandfather?"


Alex says
August 15, 2014 @ 15:26

I like this one. Lots of math/algebra involved. Would you mind if I posted an explanation of the math involved?


Dan says
August 15, 2014 @ 16:01

I wouldn’t mind at all. You’re more than welcome to add to the explanation.


Alex says
August 15, 2014 @ 19:45

https://docs.google.com/file/d/0B2b7hy0AzWqEZnJhSTBvOTBzWTg/edit?usp=docslist_api

This link is a explanation on how to do the math for this one.

The only thing I would say about this teaser is that the wording was very confusing but made more sense when I saw the answer. I don’t know how to fix the wording though so I guess the gripe is moot.

Thanks for posting these I’ve hand many hours of enjoyment on their behalf as well as they work well for Friday games in the workplace. A mass email to everyone including a teaser or 2. I sent this one out today and one guy got it withing 9 minutes by guess and check.


Dan says
August 18, 2014 @ 16:16

Thanks for the great explanation Alex! I struggled with the wording and am open to suggestions if you (or anyone else) comes up with them.


Amit says
August 21, 2014 @ 04:01

I went through the explanation by Alex. Wouldn’t it be simpler if you solve like this.
M+D+G=120
M=D/7, or D=7M
M=G/12, or G=12M
thus, M+7M+12M=120
or, 20M=120
therefore M=6.


vignesh says
June 27, 2016 @ 22:54

Thank you very much, amit.


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