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Confusing question

by jimmiejaz » Wed Dec 03, 2008 2:17 pm
The average weight of 15 items is 8 kg. The least average weight of 5 items of these 15 is 5 kg. If no item weighs less than 5 kg, what is the maximum number of items that can have the same weight?

3
5
6
10
14

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Re: Confusing question

by Stuart@KaplanGMAT » Wed Dec 03, 2008 3:04 pm
jimmiejaz wrote:The average weight of 15 items is 8 kg. The least average weight of 5 items of these 15 is 5 kg. If no item weighs less than 5 kg, what is the maximum number of items that can have the same weight?

3
5
6
10
14
We know that the 5 lightest items average 5kg and none of them weigh less than 5kg. In other words, the 5 lightest items are 5kg each.

We want to know the maximum possible number of items that could weigh the same amount.

Well, we know that at least 5 of the items are 5kg each. Could there be more?

Sure! In fact, we could have 14 items at 5kg each and 1 super-heavy item to make them average 8kg. Choose (E).

Many people would assume that you can't have more items at 5kg and then make the remaining 10 items over 8kg and equal, thereby choosing (D) instead.
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by jimmiejaz » Wed Dec 03, 2008 3:06 pm
Thanks, for the explanation Stuart.

yes i marked D. :oops:
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by cramya » Wed Dec 03, 2008 4:08 pm
Nice explanation Stuart!

Looks more like a conceptual question (good one).

I subtracted 25 from 120 to get to 95.

Initially went for 10 items 9.5 each but looked at 14 and decided to use 9*5 + 2 items 25 kg each(since we are asked to maximize the number).The least average weight of 5 items of these 15 means any 5 taken from 15 could have the least avergae weight of 5 with none individually less than 5 kg's each.

Since it was more conceptual than algebric I did use the answer choices to get to the correct answer!

E)
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Re: Confusing question

by logitech » Wed Dec 03, 2008 5:59 pm
jimmiejaz wrote:The average weight of 15 items is 8 kg. The least average weight of 5 items of these 15 is 5 kg. If no item weighs less than 5 kg, what is the maximum number of items that can have the same weight?

3
5
6
10
14

OA TBA
As pointed out by Stuart, we can have as many as 5 kgs we want and a heavy one(1)

15-1= 14 B-)
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