A sample of experienced typists revealed that their mean typing speed is 87 words per minute and the median typing speed is 73 words per minute. The standard deviation of typing speed is 16.9 words per minute. What is the Pearson coefficient of skewness?
A)−2.5
B)−4.2
C)+4.2
D)+2.5

Question

Quizplus · Accepted Answer

The Pearson coefficient of skewness can be calculated as: (mean - mode) / standard deviation. However, since the mode is not given in this question, we can use the relationship between the mean, median, and skewness. 
If the mean is greater than the median, then the distribution is positively skewed. If the mean is less than the median, then the distribution is negatively skewed. 
In this case, the mean (87) is greater than the median (73), indicating a positively skewed distribution. Therefore, the Pearson coefficient of skewness will be a positive number.

Plugging in the values given: 
Pearson coefficient of skewness = (mean - median) / standard deviation
Pearson coefficient of skewness = (87 - 73) / 16.9
Pearson coefficient of skewness = 0.83

Since the value is positive, the answer is (D) +2.5.

A Sample of Experienced Typists Revealed That Their Mean Typing