A certain ball team has an equal number of right- and left-h

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A certain ball team has an equal number of right- and left-handed players. On a certain day, two-thirds of the players were absent from practice. Of the players at practice that day, one-third were left handed. What is the ratio of the number of right-handed players who were not at practice that day to the number of left handed players who were not at practice?

A. 1/3
B. 2/3
C. 5/7
D. 7/5
E. 3/2

OA: C

Is there a strategic approach to this question?

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by GMATGuruNY » Sun Oct 01, 2017 4:34 pm
ardz24 wrote:A certain ball team has an equal number of right- and left-handed players. On a certain day, two-thirds of the players were absent from practice. Of the players at practice that day, one-third were left handed. What is the ratio of the number of right-handed players who were not at practice that day to the number of left handed players who were not at practice?

A. 1/3
B. 2/3
C. 5/7
D. 7/5
E. 3/2
This is an EITHER/OR group question.
Each player is EITHER left-handed OR right-handed.
Each player is EITHER present OR absent.
For an EITHER/OR group problem, use a GROUP GRID to organize the data.

Let L = left-handed, R = right-handed, P = present, A = absent.
To get a good number for the total, multiply all of the DENOMINATORS of the fractions described in the problem.
An equal number of left-handed and right-handed players implies 1/2.
2/3 were absent.
Of the players who attended practice, 1/3 were left-handed.
Let the total = 2*3*3 = 18.
Here's the grid:
_______________L_______R_______Total

P:

A:

total:____________________________18
Now let's fill in the grid step by step.
As soon as we know 2 entries in a row or a column, we can calculate the remaining entry in that row or column.

A certain ball team has an equal number of right- and left-handed players.
Two-thirds of the players were absent from practice.

_______________L_______R________Total

P:________________________________6

A:_______________________________12

total:__________9_______9_________18
Of the players at practice that day, one-third were left handed.
_______________L______R________Total

P:_____________2______4___________6

A:_______________________________12

total:__________9______9__________18
Complete the grid:
_______________L______R_________Total

P:_____________2______4__________6

A:_____________7______5_________12

total:__________9______9_________18
Answer the question:
(right-handed and absent)/(left-handed and absent) = 5/7.

The correct answer is C.
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by Brent@GMATPrepNow » Sun Oct 01, 2017 5:34 pm
Mitch's Group Grid approach (aka Double Matrix Method) can be used for most questions featuring a population in which each member has two characteristics associated with it.
Here, we have a population of players, and the two characteristics are:
- left-handed or right-handed
- absent from practice or present at practice

These kinds of questions are VERY POPULAR on the GMAT, so be sure you know how to solve them.

To learn more about the Double Matrix Method (aka Group Grid), watch our free video: https://www.gmatprepnow.com/module/gmat- ... ems?id=919

Once you're familiar with this technique, you can attempt these additional practice questions:

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by Scott@TargetTestPrep » Fri Jan 05, 2018 6:47 am
ardz24 wrote:A certain ball team has an equal number of right- and left-handed players. On a certain day, two-thirds of the players were absent from practice. Of the players at practice that day, one-third were left handed. What is the ratio of the number of right-handed players who were not at practice that day to the number of left handed players who were not at practice?

A. 1/3
B. 2/3
C. 5/7
D. 7/5
E. 3/2
We can let the number of right- and left-handed players be 9 (we are using the number 9 because it's a multiple of 3). Thus, there are a total of 18 players on the team.

Since we are given that on certain day, â…” of the players were absent, 12 players were absent and 6 players were present. Of the 6 players who were present, â…“ were left-handed, so 2 players were left-handed and 4 players were right-handed.

Since we've assumed there were 9 right-handed players and 9 left-handed players on the team, 5 right-handed players were absent and 7 left-handed players were absent. So, the ratio of absent right-handed players to absent left-handed players is 5 to 7.

Answer: C

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