Suppose that 15 students take a quiz and everyone in the class scores an 80. The standard deviation of scores for this quiz is ____________?
Zero, there is no deviation from they mean.
To find the standard deviation of the scores for this quiz, you need to follow these steps:
Step 1: Calculate the mean (average) of the scores.
Since everyone in the class scored an 80, the sum of all the scores is 15 * 80 = 1200. Divide this sum by the total number of students: 1200 / 15 = 80.
Step 2: Calculate the variance of the scores.
To find the variance, subtract the mean from each individual score, square the result, and then sum up all these squared differences. In this case, all the scores are the same (80), so the variance will be zero.
Step 3: Calculate the standard deviation.
The standard deviation is the square root of the variance. Since the variance is zero, the standard deviation will also be zero.
Therefore, the standard deviation of the scores for this quiz is 0.