# Thread: coding method to find sd and mean

1. ## coding method to find sd and mean

i am going to use coding method to do this question. a= assumed mean a=46.5 , i am not sure about b . what numer should i use for b ? why ? u=(x-a)/b

3. ## Re: coding method to find sd and mean

If your text book says "using the transformation $u_i= \frac{x_i- a}{b}$" then your text book will have to say what "a" and "b" mean- otherwise that is meaningless. I suspect that at least a clue follows the last item you give: it says the standard deviation of x is b times the standard deviation of u. What does your text book say about the standard deviation of u that makes that a useful transformation?

4. ## Re: coding method to find sd and mean

Originally Posted by HallsofIvy
If your text book says "using the transformation $u_i= \frac{x_i- a}{b}$" then your text book will have to say what "a" and "b" mean- otherwise that is meaningless. I suspect that at least a clue follows the last item you give: it says the standard deviation of x is b times the standard deviation of u. What does your text book say about the standard deviation of u that makes that a useful transformation?
sorry. a=assumed mean which is alraedy given in the question ( a=46.5) , b=scaling factor (usually class width) ...

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