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A hand purse contains 6 nickels, 5 pennies and 4 dimes.

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Re: A hand purse contains 6 nickels, 5 pennies and 4 dimes.

by durgesh79 » Thu Jun 12, 2008 11:32 pm
netigen wrote:A hand purse contains 6 nickels, 5 pennies and 4 dimes. What is the probability of picking a coin other than a nickel twice in a row if the first coin picked is not put back?
Probability of picking a P or D in first pick = (5+4)/15 = 9/15 = 3/5
Probability of picking a P or D in second pick = 8/14 = 4/7

Combined probability = 3/5 * 4/7 = 12/35
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by netigen » Thu Jun 12, 2008 11:35 pm
You are assuming that the Q means we have to pick any non nickel coin twice.

I read the question as saying that the same non nickle coin has to be picked twice.
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by durgesh79 » Thu Jun 12, 2008 11:47 pm
In that case the answer will be

P : 5/15 * 4/14
D : 4/15 * 3/14

Final probability = (20 + 12) / 15*14 = 16/105

The answer will depend on the options available . If both 12/35 and 16/105 are options, then its a tricky question. :?
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by netigen » Thu Jun 12, 2008 11:51 pm
Question is can this question be interpreted in multiple ways or am I just over reading :)
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by jasonc » Fri Jun 13, 2008 12:47 am
you're overreading :)
that, or its not an OG question :p
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by durgesh79 » Fri Jun 13, 2008 9:41 am
May be I'm overthinking but looks like this one is an actual GMAT problem. Refer below thread, why auther would think that he might be in trouble. :wink:

https://www.beatthegmat.com/probability-t10305.html
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by netigen » Fri Jun 13, 2008 12:30 pm
This is a MGMAT Q
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by Scott@TargetTestPrep » Wed Nov 20, 2019 5:53 pm
netigen wrote:A hand purse contains 6 nickels, 5 pennies and 4 dimes. What is the probability of picking a coin other than a nickel twice in a row if the first coin picked is not put back?
The probability of picking a coin that is not a nickel twice in a row is 9/15 * 8/14 = 3/5 * 4/7 = 12/35.

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by [email protected] » Thu Dec 12, 2019 12:22 pm
Hi All,

We're told that a hand purse contains 6 nickels, 5 pennies and 4 dimes. We're asked for the probability of picking two coins OTHER than nickels if the first coin picked is NOT put back. This question is a straight-forward Probability question, so we just have to work step-by-step and do the necessary calculations...

There are 6+5+4 = 15 total coins.

The probability of NOT choosing a nickel on the first try is 9/15 = 3/5

Since we do NOT put that coin back, we have removed one non-nickel from the purse and the probability of NOT choosing a nickel on the second try is 8/14 = 4/7

Thus, the overall probability of pulling two NON-nickels is (3/5)(4/7)...

Final Answer: [spoiler]12/35[/spoiler]

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
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