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How Old is Grandpa

Math brain teasers require computations to solve.

 

Puzzle ID:#1404
Fun:*** (2.55)
Difficulty:*** (2.49)
Category:Math
Submitted By:gokaran***

 

 

 



Grandpa says, "My grandson is about as many days as my son is weeks, and my grandson is as many months as I am in years. My grandson, my son and I together are 100 years. Can you tell me my age in years?"

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Comments

cat
Dec 12, 2001

neato make more!!!!!!!!!!!!!!!!!!!!!

:]
pusandave
Mar 29, 2002

I am impressed with your ability to explain the answer. It's nice to see it spelled out instead of just "60".
paul726Aus*
Mar 05, 2006

I agree with liking to see the answer explained, but I don't think so much detail was necessary.
tonjawithaj*us*
Aug 09, 2006

This one made me think!
jasmin215**
Oct 29, 2007

WOW! i gave up after i tried it for like 2 mins and after that respose lol gave up even quicker. it sounds right t me since you had a long explain.. must be right good job!!!!!!!
javaguru*us*
Feb 08, 2009

There is a MUCH easier way to do this--I did this in under 10 seconds in my head.

The ratio of ages is 12::7::1. 12+7+1=20. 100/20=5. 5*12=60.

This works for all these ratio problems. Setting up equations is a waste of time.

Jimbo*au*
Apr 15, 2009

If I am x years then my grandson is x/12 years and my son is (x/12)*365/52 which is approximately 7x/12. Thus x + x/12 + 7x/12 = 100 or x = 60. The diffiiculty here is to realise that there are about 7 times as many days as weeks in a year. I like Java's solution better.
bookrage*
Jan 30, 2015

hardest puzzle I've solved to date. I just created an account yesterday but have been coming here for years. Challenging and actually requires a lot more algebra than a lot of stuff here. Liked it. I had to set up the equations to make the problem make sense but did the calculations in my head once I figured out how the problem worked. nice challenge though.

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