<h3>
Answer:</h3>
A)
- motorcylcist: 2 hours
- bus: 2.5 hours
- truck: 3 hours
- bicyclist: 7.5 hours
B) It is a matter of definition: speed = distance/time. <em>Speed</em> is proportional to distance and <em>inversely proportional to time</em>.
<h3>
Step-by-step explanation:</h3>
Speed is defined as the ratio of distance to the time required to cover that distance:
... speed = distance/time
Solving this relation for time, we have ...
... <em>time = distance/speed</em>
a) For each of the modes of transportation, we can find the time by using this relation.
... motorcyle: (150 km)/(75 km/h) = 2 h
... bus: (150 km)/(60 km/h) = 2.5 h
... truck: (150 km)/(50 km/h) = 3 h
... bicycle: (150 km)/(20 km/h) = 7.5 h
b) For a given distance, speed and time are inversely related as a matter of definition.
