linear regression question

Regression results for increased travel time between distances in London: Motorcycles: Y= 2.50 + 1.93X Which of the following is the closest estimate of the increased travel time for a motorcycle commuter that moved 8 km further from his workplace in London? a. 31 minutes b. 15 minutes c. 5 minutes d. 0.154 minutes The answer is 15 minutes, calculated as: 1.93 x 8 km= 15.44 minutes. However, I thought to get the predicted value for Y you would add 2.50 to 15.44. That’s what the equation looks like. I am missing something. PLEASE HELP!!!

he is moving 8 KM Further So the difference in time = 2.5 + 1.93 (X+8) - (2.5 + 1.93 X) = 15.44

I think adding 2.50 in this case would be total travel time. They are asking for increased travel time here.

So, it’s assuming you are already starting off at 2.5 and just asking how much FURTHER. Gotcha. cpk123, do you ever get tired of answering my dumb questions?

nope… they are not dumb. These are precisely the same mistakes we would end up making on the exam under real pressure conditions. Better to get that out of the system first…