This is a story of four boys - Chinku, Dinku, Pinku and Tinku.
One day all of them decide to save their money in a bank(Joint Account).
They select a bank called “Lena Bank”
The bank's specialty is: In every month the money gets doubled.
In 2nd month, Chinku withdraws 100-Rs from bank.
In 3rd month, Dinku withdraws 100-Rs from bank.
In 4th month, Pinku withdraws 100-Rs from bank.
In 5th month, Tinku withdraws 100-Rs from bank.
Then their balance in the bank becomes zero.
How much amount had the boys put in the bank?
8 comments:
To solve you need to start from back.
5th Month he withdraws 100 Rs so in month 4 they must have 50.
4th Month he withdraws 100 + 50 for 5th month so balance 150.
3rd month he withdraws 100 + 75 for 4th month so balance 175.
2nd month he withdraws 100 + 87.5 for 3td month so balance 187.5
1st month Deposit Rs. 93.75
Thats not right Anonymous. 1st month deposit isn't 93.75. It will be the closing balance for the first month. Question is, how much they had put in the bank. You've go one more step further. The answer should be 46.875
Correct Answer is 96.875
Correct ans is Rs.93.75......
93.75 * 2 - 100 = 87.5
87.5 * 2 - 100 = 75
75 * 2 - 100 = 50
50 * 2 - 100 = 0
Invested
93.75 Month Int@200 W/d total
jan 187.5 0 93.75
feb 175 100 87.5
mar 150 100 75
apr 100 100 50
may 0 100 0
Thts the maths behind this..cheers!!!
The answer should be half of 93.75 i.e 46.875.
The reason is since every month their money in bank gets doubled.so by 2nd month also money would have been doubled.also they have asked about the amount deposited by them
If its since the beginning I say 400 because over a period of time they each took 100 out hence they balance became 0.
its simple algebra
let say money deposited is x
month 1: money = x
month 2: money = 2x-100
month 3: money = 4x-300 (2*100+100(previous bal))
month 4: money = 8x-700 (4*100 + 300)
month 5: money = 16x-1500 (5*100+ 1000 previous bal))
as the final balance is zero,
16x-1500=0
==> 1500=16x
==> x=93.75
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