2-62
A truck travels at 80 km/h for 30 min, then at 60 km/h for 1.5 hr. Assuming 2 significant digits in the given numbers, calculate the truck's
(a) total distance traveled, and
(b) average speed.

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Which statement is correct?
 A    The truck travels at a constant speed for the whole trip.
B    The truck travels at two different speeds for the whole trip.
C    The truck's speed is constantly changing.