Question

Michael drove to a friend’s house at a rate of 40 mi/h. He returned by the same route at a rate of 45 mi/h. The driving time for the round trip was 4 h. What is the total distance Michael traveled?

Answer 1

The answer is Edgenuity is b. about 169.4 miles

Answer 2

169.41 mi

Explanation:

Let the time required for the outbound trip be t1 and that for the inbound (return) trip be t2. Then t1 + t2 = 4 hr. We can eliminate one variable by solving this equation for it: t1 = 4h - t2.

Then the time spent on the outbound trip was t1 = d / (40 mph) and that on the inbound trip t2 = d / (45 mph). We want to find the total distance traveled, which will be 2d.

d d

t1 + t2 = 4 hr becomes ---------------- + --------------- = 4 hr

40 mph 45mph

We must solve for d. The LCD here is 40*45, or 1800; thus, this equation becomes

45d + 40d = 4(1800), or 85d = 7200. Thus, d = 84.7 miles.

Michael drives this same distance going and returning, so the total distance he drives is 2(84.7 miles) = 169.41 mi