Soccer team - Veritas Question Bank

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Soccer team - Veritas Question Bank

by shenoydevika » Tue Feb 19, 2013 2:39 am
Seven students are trying out for the school soccer team, on which there are three available positions: fullback, sweeper, and goalie. Each student can only try out for one position. The first two students are trying out for fullback. The next two students are trying out for sweeper. The remaining three students are trying out for goalie. However, the fourth student will only play if the second student is also on the team, and the third student will only play if the fifth student is on the team. How many possible combinations of students are there to fill the available positions?

A - 3
B - 5
C - 7
D - 10
E - 12

OA - B

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by Anurag@Gurome » Tue Feb 19, 2013 3:23 am
shenoydevika wrote:Seven students are trying out for the school soccer team, on which there are three available positions: fullback, sweeper, and goalie. Each student can only try out for one position. The first two students are trying out for fullback. The next two students are trying out for sweeper. The remaining three students are trying out for goalie. However, the fourth student will only play if the second student is also on the team, and the third student will only play if the fifth student is on the team. How many possible combinations of students are there to fill the available positions?
The selection groups are {1, 2}, {3, 4}, and {5, 6, 7}
We can select only one number from each group.

Now, 4 can be selected only if 2 is selected
And, 3 can be selected only if 5 is selected

If 1 is selected, we cannot select 4 and we have to select 3. Then we cannot select 6 or 7, we have to select 5 ---> Only one combination

If 2 is selected, we can select either 3 or 4.
  • If we select 3, then we cannot select 6 or 7, we have to select 5 ---> Only one combination

    If we select 4, then we can select either 5 or 6 or 7 ---> Three combinations
Hence, a total of (1 + 1 + 3) = 5 combinations are possible.

The correct answer is B.
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by shenoydevika » Tue Feb 19, 2013 6:08 am
Hey Anurag!

I started off with this method then got all confused mid-way and had to guess. (Ended up guessing wrong)
Is there an alternate method to solve this problem?
Veritas explained the answer but I didn't understand it...

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by GMATGuruNY » Tue Feb 19, 2013 8:00 am
shenoydevika wrote:Seven students are trying out for the school soccer team, on which there are three available positions: fullback, sweeper, and goalie. Each student can only try out for one position. The first two students are trying out for fullback. The next two students are trying out for sweeper. The remaining three students are trying out for goalie. However, the fourth student will only play if the second student is also on the team, and the third student will only play if the fifth student is on the team. How many possible combinations of students are there to fill the available positions?

A - 3
B - 5
C - 7
D - 10
E - 12

OA - B
To keep track of the number of options for each position, draw a TREE.
Start with the MOST RESTRICTED position, which is SWEEPER.
If Sweeper = 3, then Goalie = 5.
If Sweeper = 4, then Fullback = 2.
Here's the tree so far:
Image

Now complete the tree, drawing the number of options for the remaining position in each case:
Image

The number of ways to choose the players is equal to the number of boxed outcomes on the right.
Total ways = 5.

The correct answer is B.
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