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# How do you do this S1 question? Watch

1. I am told to find the standard deviation of this data x 11 13 15 20 25

I know that standard deviation is the square rooting of the variance but how would you go about this bearing in mind in includes x's?
2. what was the standard diviation ? and what exactly are you trying to find out x or the varience?
3. you may have to find the standard deviation in terms of x? Unless there's any other information given so that you can actually work out x using that?
4. Sum them all up, you should get something like:

Where A is a real number.

Then divide that number by the total of numbers of values you have, in your case it is 6 giving you something like this giving you the mean..

Then for each value from your set of values, subtract the mean and square the value you get. For these set of values, we will call them squared values.

Add the squared values all up and then work out the mean of the squared values by dividing by 6... This is your variance...

Then square root that value and you have you standard deviation, you should end up with an algebraic equation.
5. I've just been looking at this

It tells me that you can come up with a good estimate for sd by range divided by 4.

An estimate then would be (25-x)/4

Is that any use to you?
6. Posted from TSR Mobile

Thanks I worked in the end you don't use include the x.

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Updated: May 15, 2013
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