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Manager
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From a group of three boys and four girls, a line of [#permalink]
 15 May 2006, 19:31
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From a group of three boys and four girls, a line of children ordered from left to right is to be selected to salute the flag. If four children are in the line, how many different such lines can be formed?
(A) 35
(B) 70
(C) 210
(D) 420
(E) 840
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Director
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From a group of three boys and four girls, a line of children ordered from left to right is to be selected to salute the flag. If four children are in the line, how many different such lines can be formed?
4+3 = 7 children
# of ordered lines = 7x6x5x4 = 840
Answer is E
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GMAT Club Legend
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Total 7 children. We use permutations for this one as order counts as a seperate group. Total = 7P4 = 840
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1) We need to select 4 children out of 7 which equals 4C7
2) Order does matter so on first place any of 4, 2nd place any of 3 and so on...Answer 4!4C7=840
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