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Averages?!

by ellexay » Wed Feb 11, 2009 5:02 pm
What was Adrian’s average percentage in the last 2 tests?
1. His average for the last 3 tests is 80%.
2. He got 70% on his first test and 80% on his second test.

• A
• B
• C
• D
• E (correct answer)

Feedback: Statement (1) gives us insufficient data as it gives the average percentage for 3 tests. It also does not inform us about the total score for all the three tests or the exact score in any of the tests. Thus, the answers can be (B), (C), or (E). The next statement gives us only the percentage obtained in the first test, and not the second test. It is not simply a matter of averaging 70 and 80 as the two tests could have a different maximum score. Thus, both the statements are unable to solve the problem and the right answer is (E).


I am confused by this solution. Please guide me through why it is not (B). Thank you all.

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by ramana » Wed Feb 11, 2009 10:37 pm
Hi,

Its not B.

Dont carry the information from A.
Just forget A and read B,you cannot find the solution with first and last value.


Thanks

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Re: Averages?!

by logitech » Thu Feb 12, 2009 12:35 am
ellexay wrote:What was Adrian’s average percentage in the last 2 tests?
1. His average for the last 3 tests is 80%.
2. He got 70% on his first test and 80% on his second test.

• A
• B
• C
• D
• E (correct answer)

Feedback: Statement (1) gives us insufficient data as it gives the average percentage for 3 tests. It also does not inform us about the total score for all the three tests or the exact score in any of the tests. Thus, the answers can be (B), (C), or (E). The next statement gives us only the percentage obtained in the first test, and not the second test. It is not simply a matter of averaging 70 and 80 as the two tests could have a different maximum score. Thus, both the statements are unable to solve the problem and the right answer is (E).


I am confused by this solution. Please guide me through why it is not (B). Thank you all.
What a bad question.
ellexay wrote:What was Adrian’s average percentage in the last 2 tests?
1. His average for the last 3 tests is 80%.
2. He got 70% on his first test and 80% on his second test.

So he might had 100 tests

and question is asking the 99th and 100th.

1) 98,99 and 100 - INSUF
2) Irrelevant 1, 2

Hence, E
LGTCH
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by ellexay » Thu Feb 12, 2009 4:02 am
Thanks...I think I'll be using official sources from now on. :P

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by naaga » Thu Feb 12, 2009 6:58 am
Logitech ...excellent explantion...really wonderful.....