computer program: calculate the mean and standard deviation of exam scores?

Answer 1

Here's an example in C that can easily be implemented in C++, Java, and other languages:

#include // for the pow() and sqrt() functions

// this array contains the raw scores, where scores[i][j] contains the student i's score on exam j
// picture this as a table with N rows and M columns - each row contains a student's score for all exams and each column contains all scores for a particular exam
double scores[N][M]; //N students with M exam scores
double mean, sum, stddev; // variables for calculating means & std deviations
unsigned int i, j, // counter variables

// for each exam...
for (i = 0; i < M; i++)
{
    sum = 0.0;
    // for each student...
    for (j = 0; j < N; j++)
    {
        sum = sum + scores[j][i];
    }
    mean = sum / N; // mean for exam i
    // go back and get the standard deviation
    sum = 0.0;
    for (j = 0; j < N; j++)
    {
        sum = sum + pow(scores[j][i] - mean, 2.0); // pow() function squares this
    }
    stddev = sqrt(sum / N); // standard deviation for exam i
}

Answer 2

The % coefficient of variation =100σ/µ =14 so 7µ=50σ The standard score of 1020 is (1020-µ)/σ = 2 and you have two equations from which you can find µ and σ.

Answer 3

You can do both in Excel:
=AVERAGE(cell range)
=STDEV(cell range)

Answer 4

do it in exel