defective ATM machine

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defective ATM machine

by sanju09 » Fri Aug 06, 2010 10:17 pm
A defective ATM machine contains only 100-dollar notes and dispenses one extra note than requested. A man initially wanted to draw $1500 from this machine but ended up carry home $2300 following successive withdrawals. What was the maximum withdrawal of all made by him?

(1) The man made 8 withdrawals from the machine.
(2) One can make as many withdrawals as wished from this machine.


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by santoostar » Mon Aug 09, 2010 5:56 am
Well, to maximise the amount in a single withdrawl we must minimize the amount in the rest of the withdrawls.

Since the ATM dispenses only 100 notes the lowest is 100.

100*7 times----> (100+100)*7---> 1400.
the rest of the amount needs to be withdrawn in the last withdrawl.

2300-1400 = 900----> the maximum amt is 800.

I would go with A....Hope this is correct..

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by sanju09 » Tue Aug 10, 2010 1:19 am
santoostar wrote:Well, to maximise the amount in a single withdrawl we must minimize the amount in the rest of the withdrawls.

Since the ATM dispenses only 100 notes the lowest is 100.

100*7 times----> (100+100)*7---> 1400.
the rest of the amount needs to be withdrawn in the last withdrawl.

2300-1400 = 900----> the maximum amt is 800.

I would go with A....Hope this is correct..
Does it read "What could be the maximum (possible) withdrawal of all made by him?"?
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by clammiestqasar » Tue Aug 10, 2010 2:44 am
IMO its E

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by fmillar » Tue Aug 10, 2010 8:33 am
The answer is E.

The 1st statement gives us multiple alternatives:

- it could be 7x100 + 700 = 1400 + 1x800 + 100 = 2300. The maximum is 800.

- ....but also 7x200 + 700 = 2100 + 1X100 + 100 = 2300. The maximum is 200.

Therefore 1 is not enough

The 2nd statement does not add more information,

and the answer is E.