Question

Joe swims 2000 yards each day. For 23 days, he records his time (in minutes) and his pulse rate (in beats per minute) at the end of the 2000 yards. He finds a linear correlation. The equation of the least squares line is pulse rate 209.9-0.695(time) .

?. Is the correlation positive or negative? How do you know?

c. Predict the average pulse rate if he swims the 2000 yards in 35 minutes.

d. What time would he need to swim the distance to have a pulse rate of 130?

Answer 1

a. Here the intercept value is negative, we conclude that if time is increase by one unit pulse rate is expected to decrease by 0.695 units. That means there is negative correlation.

c. Average pulse rate for x=35 minutes.

simply put value in regression equation,

Pulse rate= 209.9-0.695(time)

=209.9-0.695(35)

=185.58

d. We have find time for pulse rate of 130

130=209.9-0.695(time)

-0.695(time)=130-209.9

-0.695(time)= -79.9

time=79.9/0.695

time= 114.96

time approximately equal to115 minutes.