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A hand purse contains 6 nickels, 5 pennies and 4 dimes.
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durgesh79
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Probability of picking a P or D in first pick = (5+4)/15 = 9/15 = 3/5netigen 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 second pick = 8/14 = 4/7
Combined probability = 3/5 * 4/7 = 12/35
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durgesh79
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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.
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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durgesh79
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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. 
https://www.beatthegmat.com/probability-t10305.html
https://www.beatthegmat.com/probability-t10305.html
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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.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?
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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
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
