Of the 12 temp.empoyee 4 will be hired as permanent. If 5 of the 12 temp.are woman, how many of the possible groups of 4 temp.employees consist of 3 woman and 1 man?
Answer please ?
#1 permutation problem
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- Brent@GMATPrepNow
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Divide this counting question into two stages:nailyad wrote:Of the 12 temp.empoyee 4 will be hired as permanent. If 5 of the 12 temp.are woman, how many of the possible groups of 4 temp.employees consist of 3 woman and 1 man?
Answer please ?
Stage 1: Select 3 women from the 5 women
Stage 2: Select 1 man from the 7 men
Stage 1: Important question: does order in which we select the 3 women matter? For example, is selecting Ann, Bea and Dawn different from selecting Bea, Ann and Dawn? The answer is no, so we can use combinations.
We can accomplish stage 1 is 5C3 ways (10 ways)
Stage 2: We can select 1 man from 7 men in 7 ways.
The total number of ways to accomplish stage 1 and stage 2 is 10 x 7 = 70
- viju9162
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Hi Brent,
Thanks for the explanation. I arrived until the answer (70), but I again divide it by 12C4. I believe that this approach should be done for determining the total number of possibilities when it asks for probability right?
Can you please guide here.
Thank you,
Viju
Thanks for the explanation. I arrived until the answer (70), but I again divide it by 12C4. I believe that this approach should be done for determining the total number of possibilities when it asks for probability right?
Can you please guide here.
Thank you,
Viju
"Native of" is used for a individual while "Native to" is used for a large group
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That's correct. Had this been a probability question, we could use the formula:viju9162 wrote:Hi Brent,
Thanks for the explanation. I arrived until the answer (70), but I again divide it by 12C4. I believe that this approach should be done for determining the total number of possibilities when it asks for probability right?
Can you please guide here.
Thank you,
Viju
Probability of desired outcome = Number of desired outcomes/number of total possible outcomes
in which 12C4 (the number of ways of selecting unordered subgroups of 4 from big group of 12) would be the denominator and 70 the numerator.
But in this question we don't care about the number of possible groups; instead, we just care about "how many of them" have 3 women and 1 man.
So, the key was the wording of the question. Because it is asking "how many" and because we are dealing with indivisible objects (people), we need a positive integer--not a proportion or fraction--in order to answer this question. If the question had asked for probability or fraction, then that would have been the correct aproach.
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