The endurance of both track athletes and gymnasts is recorded in terms of maximum volume of oxygen and is measured in milliliters per kilogram of body weight per minute.

track athletes gymnasts
89.2 72.1
45.3 78.5
89.1 66.2
57.3 47.3
61.5 63.1
80.1 89.3
47.2 65.3

what is the difference of means, rounded to the nearest hundredth, for the two groups?

a. dx = 1.73
b. dx = 1.69
c. dx = 67.1
d. dx = 68.7