13) A study of men aged 20
20 to 40
40 investigated the relationship between the
average number of hours of exercise per week x
x and average number of hours of sleep per day y
y. The regression line was found to be y=8.5−0.2x
y=8.5-0.2x. Which of the following is a true statement?
a) For every additional hour of weekly exercise there is a corresponding 0.2
0.2 decrease in daily hours of sleep
b) We can correctly predict that a 60
60 year-old man who exercises 6
6 hours per week sleeps on average 7.3
7.3 hours per day
c) For every additional hour of weekly exercise there is a corresponding 8.5
8.5 increase in daily hours of sleep.
d) Increasing amount of weekly exercise causes a decrease in daily hours of sleep.