As part of a wide-ranging study of health and nutrition, investigators collected information for a random sample of 4023 college students.Among other statistics they found that for the students in the study the standard deviation in the students' weights (x) wassx= 10 kg,the standard deviation in the maximum amount the students could bench-press (y) wassy= 20 kgand thecorrelationbetween these two variables wasrxy 0.6.

These statistics tell us that. . .

a). . . the students who weigh 60 kgs can bench-press 12 kgs more, on average, than the students who weigh 50 kgs.

b). . . on average, students can bench press 60% of their own weight.

c). . . on average, students who weigh 70 kgs can bench press 20 kgs more than students who weight 60 kgs.

d). . . students who gain 15 kgs will increase their maximum bench-press weight by 18 kgs, on average.