Question 159211: A train travels at an average speed of 20 mph through urban areas, 50 mph
through suburban areas, and 75 mph through rural areas. If a trip consists of
traveling half an hour through urban areas, 3-1/2 hours through suburban areas,
and 3 hours through rural areas, what is the train’s average speed for the entire
trip?
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! A train travels at an average speed of 20 mph through urban areas, 50 mph
through suburban areas, and 75 mph through rural areas. If a trip consists of
traveling half an hour through urban areas, 3-1/2 hours through suburban areas,
and 3 hours through rural areas, what is the train’s average speed for the entire
trip?
.
You will need to apply the "distance formula":
d = rt
where
d is distance
r is rate or speed
t is time
.
Distance traveled through urban areas:
"speed through urban" * "time traveled"
20 * 1.5 = 30 miles
.
Distance traveled through suburban areas:
"speed through suburban" * "time traveled"
50 * 3.5 = 175 miles
.
Distance traveled through rural areas:
"speed through rural" * "time traveled"
75 * 3 = 225 miles
.
Total distance traveled:
30+175+225 = 430 miles
Total time traveled:
1.5+3.5+3 = 8 hours
.
Since:
r = d/t
430/8 = 53.75 mph
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