Question

A truck with a heavy load drove from Boston to New York at 40 mph. After unloading, it returned from New York to Boston at a speed of 60 mph. What was its average speed for the whole trip?

Answer 1

48 mph

Explanation:

Step-by-step explanation:Let one way distance be D40 = D/T1T1 = D/4060 = D/T2T2 = D/60Total distance: 2DTotal time: D/60 + D/40(2D + 3D)/120 = 5D/120 = D/24Average speed:2D ÷ D/242D × 24/D48

Answer 2

48 mph

Explanation:

Let one way distance be D

40 = D/T1

T1 = D/40

60 = D/T2

T2 = D/60

Total distance: 2D

Total time: D/60 + D/40

(2D + 3D)/120 = 5D/120 = D/24

Average speed:

2D ÷ D/24

2D × 24/D

48