Answer:
1. 100/20
2. 7 h
3. 141 km
4. 8.5 hours
5. 56 mi/h
Step-by-step explanation:
(dimensions are omitted)
1. speed = distance/time
speed = 100/20
2. time = distance/speed
time = 315/45 = 7 h
3. distance = speed*time
distance = 35.25 * 4 = 141 km
4. time = distance/speed
to the lake: time = 216/48 = 4.5 h
from the lake: time = 216/54 = 4 h
total time: 4.5 + 4 = 8.5 h
5. speed = distance/time
first trip: speed = 203/3.5 = 58 mi/h
second trip: speed = 243/4.5 = 54 mi/h
average speed = (58 + 54)/2 = 56 mi/h
