# Need help on standard deviation

Dell Inspiron 546 mini-tower desktop - c...
April 18, 2011 at 03:11:40
Specs: Windows 7, 1.5GB
 To be honest its my homework. I am stuck at the calculation part.I don't know how to write the standard deviation.#include #include #include using namespace std;const int MAX = 100;const char MaxFileName = 11;int main(){ char response='y'; int counter, recordcount; float number, next; float array [MAX]; ifstream fin; char infile [MaxFileName +1]; while (response == 'y' || response == 'Y'){ cout << "Enter the filename of the data: "; cin >> infile; fin.open (infile); if (fin.fail()) { cout << "Opening file failed.\n"; exit(1); } cout<<"Open successful.\n"; counter = 0; while (fin >> number && counter < MAX) { array [counter] = number; counter ++; } recordcount = counter; cout << "The data are: \n"; for (counter = 0; counter < recordcount; counter ++) { cout << array [counter] << " "; } cout<>response;}system("pause");return 0;}

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#1
April 18, 2011 at 04:19:12
 http://en.wikipedia.org/wiki/Standa...Unless you have a specific question?How To Ask Questions The Smart Way

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#2
April 18, 2011 at 04:41:30
 My task is:Calculate the standard deviation from a given set of data in a text file. Read and store the data in an array. Create user-defined functions to implement the input and standard deviation calculation separately.http://en.wikipedia.org/wiki/Standa... random variable:using summation notationDo not use any pre-defined functions n the standard function library to determine standard deviation or average. Use constant to identify fixed percentages and value used.Example:Enter the name of the data filecensus1.txtThe data are:1 4 7 5 6 9 15 11 8 2The Standard Deviation is: 4Y or y continues, any other character quits -> yEnter the name of the data filecensus2.txtThe data are:10 19 11 25 13 15 8 17 2 7The Standard Deviation is: 6.3Y or y continues, any other character quits -> q

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#3
April 18, 2011 at 21:53:59
 I don't know how to put in the standard deviation calculation and my input file repetition doesn't work.http://upload.wikimedia.org/math/e/...That is my formula for the code.The u thing is actually x(bar).Note: N = Total count of x values. Assume typical sample size 30.

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#4
April 19, 2011 at 16:56:58
 The linked Wikipedia article has a friendlier definition, which is surprising for Wikipedia math articles.How To Ask Questions The Smart Way

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#5
April 19, 2011 at 22:03:17
 Can someone tell me how to put in the calculation in my code.I am bad in math. Even if i know the formula I don't know how to put it into the code.

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