Was 70 the average (arithmetic mean) grade on a class test? : GMAT Data Sufficiency (DS)
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# Was 70 the average (arithmetic mean) grade on a class test?

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Was 70 the average (arithmetic mean) grade on a class test? [#permalink]

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08 Oct 2005, 07:58
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Was 70 the average (arithmetic mean) grade on a class test?

(1) On the test, half of the class had grades below 70 and half of the class had grades above 70.
(2) The lowest grade on the test was 45 and the highest grade on the test was 95.
[Reveal] Spoiler: OA

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08 Oct 2005, 08:54
Hmm E I think...i was struggling between C and E...

(a) is insuff..say half the students score 0 and the other half score 100...

you do not know the distribuition....

(b) it just gives us the range, If we knew the std. Deviation we could get the Avg...

together Insuff..(say in B if all students score 45, and all the other half scored 95....)
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08 Oct 2005, 09:31
i think E

We need the number of students in the class and more info. on the grades to find the mean.
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08 Oct 2005, 10:34
Click E --> Click Next --> Click Confirm

There is no way, to find out the average of the information given.

1 & 2 together... could be 50 times grade 45 and then 49 times grade 71 and one time grade 95...... or there could be another distribution, which has an effect on the average.
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08 Oct 2005, 19:25
nero44 wrote:
Click E --> Click Next --> Click Confirm

There is no way, to find out the average of the information given.

1 & 2 together... could be 50 times grade 45 and then 49 times grade 71 and one time grade 95...... or there could be another distribution, which has an effect on the average.

Agree! I posted this coz I was calculating the average using B by assuming (for some strange reason) that all the scores inbetween would be evenly placed!

OA is E!
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Re: Was 70 the average (arithmetic mean) grade on a class test? [#permalink]

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26 Sep 2013, 04:40
Is answer choice A.. a trap answer in this question?
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Re: Was 70 the average (arithmetic mean) grade on a class test? [#permalink]

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26 Sep 2013, 07:54
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fozzzy wrote:
Is answer choice A.. a trap answer in this question?

I find nothing too tricky in the first statement.

Was 70 the average (arithmetic mean) grade on a class test?

(1) On the test, half of the class had grades below 70 and half of the class had grades above 70 --> {69, 71} answer YES but {69, 100} answer NO. Not sufficient.

(2) The lowest grade on the test was 45 and the highest grade on the test was 95 --> {45, 95} answer YES but {45, 69, 95} answer NO. Not sufficient.

(1)+(2) {45, 95} answer YES but {45, 69, 95, 95} answer NO. Not sufficient.

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Re: Was 70 the average (arithmetic mean) grade on a class test? [#permalink]

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09 Dec 2014, 06:22
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Was 70 the average (arithmetic mean) grade on a class test?   [#permalink] 09 Dec 2014, 06:22
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# Was 70 the average (arithmetic mean) grade on a class test?

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