If I have a group of numbers, say -70, -40, -10, 10, 15, 20, 25, 35, 40, 40, 45, 50, 50 , 70, 80, 90, 100, 100, 100, 100, 100, 100. I want the -70 to equal 100, and the 100 to equal 100. How would I formulate the expression?
I am trying to create a grading curve for my students that includes negative grades. So for example I have a student that scores a -70, and one that scores 100- I want the lowest scoring student (the one with a -70) to equal a 0, but the students that scored 100 to equal a 100. I have tried using curve formula with this, but because there are negative scores the formula is not working...
Find the arithmetical mean and standard deviation of all the students’ scores. To calculate standard deviation, subtract the mean from each score to find each score's deviation. Square each deviation, then add up all the squared deviations. Divide that sum by one less than the total number of exam scores. Take the square root of that number to find the standard deviation. Make the mean test score a C grade, regardless of the actual percentage of the mean score. That score is now the cutoff for a C. Add the standard deviation to the mean score to get the cutoff for a B grade, and add one more standard deviation for an A grade. Subtract one standard deviation from the mean to get a D grade and subtract one more to get an F grade. Add and subtract half a standard deviation from these grades to assign “plus” and “minus” grades on top of straight letter grades. Convert the raw scores of the student into curved scores based on your determined cutoffs (*calendar range).