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# Test Tomorrow: need help withThis GMATPREP Q(MEAN, Median,

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Intern
Joined: 19 Dec 2008
Posts: 8
Schools: Accounting
Test Tomorrow: need help withThis GMATPREP Q(MEAN, Median, [#permalink]

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25 Feb 2009, 07:55
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

96 84 80 70 48(\$)
4 7 4 3 2 (days)

A student worked for 20 Days. For each amount shown above in the first row, the second row gives the amount of money earned in dollars in that day. What is the median amount of money that she earned per day for the 20 days?

Options:
96
84
80
70
48
Current Student
Joined: 03 Aug 2006
Posts: 112
Re: Test Tomorrow: need help withThis GMATPREP Q(MEAN, Median, [#permalink]

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25 Feb 2009, 12:52
Arranging the dollars for 20 days:
48,48,70,70,70,80,80,80,80,84,84,84,84,84,84,84,96,96,96,96

As 20 is even take values from 10th and 11th position and divide by 2 to find the median.
84+84/2 = 84

Current Student
Joined: 03 Aug 2006
Posts: 112
Re: Test Tomorrow: need help withThis GMATPREP Q(MEAN, Median, [#permalink]

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25 Feb 2009, 12:59
Adding to the previous post..if you were trying to find the mean instead you would use the following method:

Days \$
4 x 96
7 x 84
4 x 80
3 x 70
2 x 48

1. Guesstimate an average: Let's pick 80
Now subtract 80 from each number and multiply it by the number of days

4 x (96-80) = 4 x 16 = 64
7 x (84-80) = 7 x 4 = 28
4 x (80-80) = 4 x 0 = 0 0
3 x (70-80) = 3 x -10 = -30
2 x (48-80) = 2 x -32 = -64

2. Add them (64-64+0+28-30) = -2
3. Divide the result by 20 days =-2/20 = -0.1

Add this number to the original guesstimate to get the mean (avg) = 80+(-0.1) = 80 - 0.01 = 79.9

Last edited by nookway on 25 Feb 2009, 13:00, edited 1 time in total.
Current Student
Joined: 03 Aug 2006
Posts: 112
Re: Test Tomorrow: need help withThis GMATPREP Q(MEAN, Median, [#permalink]

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25 Feb 2009, 13:00
1
KUDOS
t75803-ps-looking-for-easy-calculation-trick
Intern
Joined: 19 Dec 2008
Posts: 8
Schools: Accounting
Re: Test Tomorrow: need help withThis GMATPREP Q(MEAN, Median, [#permalink]

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25 Feb 2009, 15:43
Thaanks nookway. u r the best
Re: Test Tomorrow: need help withThis GMATPREP Q(MEAN, Median,   [#permalink] 25 Feb 2009, 15:43
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# Test Tomorrow: need help withThis GMATPREP Q(MEAN, Median,

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