Weighted Mean help please (stats) Watch

Olive123
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Ok so my problem is with part b.

What does this mean how would I go about answering this question.
Thanks !
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ghostwalker
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(Original post by Olive123)
Ok so my problem is with part b.

What does this mean how would I go about answering this question.
Thanks !
The weights will be in the ratio of 23 : 8 : 14 : 11 : ... : 23.

The sum of the weights must equal 1, so you need to scale them appropriately.


E.g.

If your data was 3,4,5, they would need to be weighted in the ratio 3 : 4 : 5.

Since 3+4+5=12, we need to multiply the ratios by 1/12 to get the weightings, viz. 3/12, 4/12, 5/12.
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Olive123
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(Original post by ghostwalker)
The weights will be in the ratio of 23 : 8 : 14 : 11 : ... : 23.

The sum of the weights must equal 1, so you need to scale them appropriately.


E.g.

If your data was 3,4,5, they would need to be weighted in the ratio 3 : 4 : 5.

Since 3+4+5=12, we need to multiply the ratios by 1/12 to get the weightings, viz. 3/12, 4/12, 5/12.
Well I have just done the sum of (1/206*23) up to the end of the observations and I got 1 . This is wrong I have no idea what im doing
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ghostwalker
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(Original post by Olive123)
Well I have just done the sum of (1/206*23) up to the end of the observations and I got 1 . This is wrong I have no idea what im doing
So, the sum of the weights is 206, and you will need to scale the weights by that factor.

So, for b), the weighting of 23, for example, will be 23/206, as it's proportional to the observation.

The weighted mean is the sum of, the product of the observation times the weight.

So the contribution from the first item will be 23\times\dfrac{23}{206}, etc.
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