Set R contains five numbers that have an average value of 55

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Re: Set R contains five numbers that have an average value of 55 [#permalink]

24 Jan 2013, 13:29

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Sachin9 wrote:

Hi ,

Here's how I did..

smallest no: s
largest no: 3s+20

since mean = median,

thought that numbers are in AP.

so average= (last no+first no)/2

therefore 55=(s+3s+20)/2
=> s=22.5

now l=20+3s
=> l=87.25

range =l-s=65..
Please let me know where I am going wrong.

Sachin, you assumed that the numbers are in AP, but problem doesn't state that.
This set S = {29, 29, 55, 55, 107} has the maximum range i.e. 78 and mean/median 55.

Note that these numbers are not in AP/sequence. Hence you cannot take average of last & first to find the mean.
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Re: Set R contains five numbers that have an average value of 55 [#permalink]

24 Jan 2013, 17:22

PraPon wrote:

Sachin9 wrote:

Thanks mate..
I thought that the numbers would be in AP since their median and mean were same.

I now understand that if the nos are in AP , then their median and mean will be same but the vice versa is not necessarily true.
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Re: Set R contains five numbers that have an average value of 55 [#permalink] 24 Jan 2013, 17:22

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Set R contains five numbers that have an average value of 55

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Set R contains five numbers that have an average value of 55

Set R contains five numbers that have an average value of 55

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