Birthday Puzzle
Bob and Betty has five children - Polly, Jolly, Molly, Lolly, and Dolly
Eldest Polly is born on 1st of January. Next is Jolly, born on 1st of February. 1st of March is again the scene of birthday celebration in their house. What is the probability of it not being that of molly's ?
Oh yes the sum of the ages of the five children equals product of their ages.
Eldest Polly is born on 1st of January. Next is Jolly, born on 1st of February. 1st of March is again the scene of birthday celebration in their house. What is the probability of it not being that of molly's ?
Oh yes the sum of the ages of the five children equals product of their ages.
Labels: logic
posted by Rajesh Lal at
7:12 PM
11 Comments:
Zero.
Ages are 5,2,1,1,1. Sum = product = 10. So the three youngest are triplets, all born on 1 March.
hm... I'd still go with 2 out of 3 chances its not Molly's BD.
-h
I agree with the first post. The ages are 5,2,1,1,1 but in the question, it doesn't say that the
1st March is the NEXT birthday, therefore, Molly could have been born on any other day. To not be the same as P or J we rule out 1st Jan and 1st Feb. M would have to be born before 1st of March to make her 1 year old at the time of the birthday in March.
It's too early in the morning to think about it........hope someone else can solve it.
March 1 could be the birthday of one of the parents.
Good point, that last one.
Molly is still one of the triplets. So if Bob, Betty and the triplets have different birthdays to each other (and to the 2 older kids) then there is a 2/3 chance that 1 March is NOT Molly's birthday.
So Hagar (above) is right, though maybe not for the right reasons.
Nice thinker here.. I agree 2/3.. either the tripplets, or one of the parents..
But.. what if the triplets were born on different days?? before/after midnight.. :p
Very good - I thought it most likely to be Bobs birthday that was being celebrated:
March 1, 1927 Robert Bork, American Public Servant
-h
Unless we know the total number of people in the house, we can't guess. Is it Grandma's birthday? How about Mom? There's no way to know for sure that it's even one of the children.
The triplets could include Jolly since the question doesn't specify that Jolly's is the only birthday on Feb 1st. It says Jolly's is the next birthday, not the next oldest.
So Mar 1st can be any of Molly, Lolly, Dolly, Bob, or Betty.
molly doesn't necessarily have to be one of the triplets. The two remaining unknowns could share a birthday with one of the known children making them triplets. It was never declared that the first b-days were exclusive to those listed. With that, and including the parent would have to make it 1/5. ...I think...
there is a 66.6% chance it is not molly's.
and their ages do not matter because it could be march of any year
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