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Maths Puzzle
On Jan 1st I put 1 rupee in bank on 2nd I put 2 on third I put 4 and it goes so on.By the end of the same month I would have come up to a particular amount.On which day I would have obtained the half of the amount ?
Read Solution (Total 5)
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- amount is doubled on next day...
so half amount will be on 30th jan - 11 years agoHelpfull: Yes(3) No(3)
- @glory
2nd day total amount was 3 which is one greater than previous day amount i.e. 1
3rd day total amount become 3+4=7 which is also one greater than double of previous day amount i.e. 1+(3*2)
similarly 4th day it will become 7+8=15 which is also 2*7+1
similarly double of amount on 30 jan should be added on 31st jan....
so i hv get half amount on 30th jan - 11 years agoHelpfull: Yes(2) No(0)
- @ jaiprakash hey plz elaborate your explanation. i did not understand.
- 11 years agoHelpfull: Yes(1) No(2)
- on first day amount is 1 on second day it becomes 3...on its next day it becomes 7....and so on...so basically we are depositing in following fashion....1,2,4,8,16....which forms a G.p....now sum of dis g.p on 31st of january= 1*(1-2^31)/1-2...and as we are intrested in the day at which the total amount would be its half so ((1/2)*1*(1-2^31))/(1-2)=1*(1-2^d)/(1-2)
=>2^(d+1)=1+ 2^31 which is not possible for any whole value of d - 11 years agoHelpfull: Yes(1) No(1)
- @ Anjul thanx.
- 11 years agoHelpfull: Yes(1) No(1)
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