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# A group of 20 values has a mean of 85 and a median of 80. A

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Founder
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A group of 20 values has a mean of 85 and a median of 80. A [#permalink]  30 May 2019, 10:28
Expert's post
A group of 20 values has a mean of 85 and a median of 80. A different group of 30 values has a mean of 75 and a median of 72.

(a) What is the mean of the 50 values?

(b) What is the median of the 50 values?

[Reveal] Spoiler: OA
(a) mean=79 (b) The median cannot be determined from the information given.

Math Review
Question: 3
Page: 296
Difficulty: medium

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Re: A group of 20 values has a mean of 85 and a median of 80. A [#permalink]  13 Oct 2019, 08:00
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KUDOS
Carcass wrote:
A group of 20 values has a mean of 85 and a median of 80. A different group of 30 values has a mean of 75 and a median of 72.

(a) What is the mean of the 50 values?

(b) What is the median of the 50 values?

[Reveal] Spoiler: OA
(a) mean=79 (b) The median cannot be determined from the information given.

Math Review
Question: 3
Page: 296
Difficulty: medium

Here,

Mean of 50 numbers : $$\frac{{(85 * 20 ) +(75 * 30 )}}{50}= \frac{3950}{50} = 79$$

For median we don't have enough information, since median is the middle number and there can be numerous possible values
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Manager
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Re: A group of 20 values has a mean of 85 and a median of 80. A [#permalink]  24 May 2020, 10:28
What would we need to be able to determine the median?
Founder
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Re: A group of 20 values has a mean of 85 and a median of 80. A [#permalink]  25 May 2020, 16:18
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Expert's post
Manager
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Re: A group of 20 values has a mean of 85 and a median of 80. A [#permalink]  25 May 2020, 23:06
Meaning if we had the starting points of both sets, then we would be able to determine the new median?

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Founder
Joined: 18 Apr 2015
Posts: 13909
GRE 1: Q160 V160
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Kudos [?]: 3680 [2] , given: 12935

Re: A group of 20 values has a mean of 85 and a median of 80. A [#permalink]  26 May 2020, 14:25
2
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Expert's post
Yes. You do know the median of the 20 set and the 50 set but is impossible to determine the median of these two combined without knowing the start and ending point

In the stem the told you which is the median and this is ok. It is data the stem provided. Ok so far so good. I take for granted.

But if I have to combine the two data sets and then see which is the median is impossible to assess.

Where I start and when I will end....who knows

I could start from 1 to 50 or from 127 to 177 the median is quite different

Now is more clear ??
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Manager
Joined: 01 Jan 2020
Posts: 114
Concentration: Marketing
Schools: Copenhagen Business School - Class of 2022
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Kudos [?]: 61 [0], given: 46

Re: A group of 20 values has a mean of 85 and a median of 80. A [#permalink]  04 Jun 2020, 02:59
Carcass wrote:
Yes. You do know the median of the 20 set and the 50 set but is impossible to determine the median of these two combined without knowing the start and ending point

In the stem the told you which is the median and this is ok. It is data the stem provided. Ok so far so good. I take for granted.

But if I have to combine the two data sets and then see which is the median is impossible to assess.

Where I start and when I will end....who knows

I could start from 1 to 50 or from 127 to 177 the median is quite different

Now is more clear ??

Clear as the Adriatic sea Sir!
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