In a study of the function of pectoral fins in fish, a graduate student examined 7 fish with the following lengths (in centimeters, cm):
30 28 29 27 31 25 29
What is the variance of these 7 fish lengths?

Question

Quizplus · Accepted Answer

To calculate the variance, first find the mean of the fish lengths: $ \frac{30 + 28 + 29 + 27 + 31 + 25 + 29}{7} = 28.43 $ cm. Then, calculate the squared differences from the mean, sum them, and divide by the number of observations minus one (for sample variance): $ \frac{(30-28.43)^2 + (28-28.43)^2 + (29-28.43)^2 + (27-28.43)^2 + (31-28.43)^2 + (25-28.43)^2 + (29-28.43)^2}{7-1} = 3.95 $ cm².

In a Study of the Function of Pectoral Fins in Fish