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60% of the marbles in a jar are red. Twenty marbles....
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Updated on: 03 May 2020, 08:45
Updated on: 03 May 2020, 08:45
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53% (02:08) wrong based on 80 sessions
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60 percent of the marbles in a jar are red. Twenty marbles are to be added to the jar, three of which will be red. If 50 percent of its marbles, after the addition, are to be red, how many marbles will be in the jar?
A) 60
B) 70
C) 80
D)90
E)100
A) 60
B) 70
C) 80
D)90
E)100
Originally posted by jackiesuepowell on 03 May 2020, 08:40.
Last edited by Carcass on 03 May 2020, 08:45, edited 1 time in total.
Last edited by Carcass on 03 May 2020, 08:45, edited 1 time in total.
Updated
Re: 60% of the marbles in a jar are red. Twenty marbles....
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03 May 2020, 08:53
03 May 2020, 08:53
Expert Reply
We can use the weighted average
Before the adding the red marble was 60% of the total. After where 50%
Clearly on the average the drag down the possible value number which is 100. Clearly D is the best option
Before the adding the red marble was 60% of the total. After where 50%
Clearly on the average the drag down the possible value number which is 100. Clearly D is the best option
Re: 60% of the marbles in a jar are red. Twenty marbles....
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03 May 2020, 09:58
03 May 2020, 09:58
Expert Reply
Here the concept is well explained
https://www.manhattanprep.com/gmat/blog ... lems-easy/
Suppose that the marble are 100 and the red are 60% . After the marble are 63 and they are the 50% that means the middle of the average is less than before.
The upper extreme is 100 but now our average is LESS so cannot be 100 but 90.
100 was when the red were 60% but now are 50% Logically the overall marble cannot be 100
Ask if you do need further assistance
https://www.manhattanprep.com/gmat/blog ... lems-easy/
Suppose that the marble are 100 and the red are 60% . After the marble are 63 and they are the 50% that means the middle of the average is less than before.
The upper extreme is 100 but now our average is LESS so cannot be 100 but 90.
100 was when the red were 60% but now are 50% Logically the overall marble cannot be 100
Ask if you do need further assistance
