A car drives 60 miles on local roads at 20 mph, and 120 miles on the highway at 60 mph, what is the ...
A car drives 60 miles on local roads at 20 mph, and 120 miles on the highway at 60 mph, what is the average speed of the entire trip?
Answer/Solution
36 mph
Steps/Work
So The Answer is Plainly A....
we have a general relation for speed , time and distance : v (velocity) * t ( time)= d (distance)
for first part we have d=60 miles , and v= 20 mph so we can obtain time : 20*t = 60 Or t= 60/20 = 3 hours the needed time to cover 60 miles
in the same way we should divide 120 to 60 to find the needed time to cover 120 miles ,so t= 2 hours
so the total time for covering total distance would be 3+2 = 5 hours and total distance is 60+120= 180 miles
Final stage : average speed is total distance divide to total time : 180/5 = 36 miles per hour....
we have a general relation for speed , time and distance : v (velocity) * t ( time)= d (distance)
for first part we have d=60 miles , and v= 20 mph so we can obtain time : 20*t = 60 Or t= 60/20 = 3 hours the needed time to cover 60 miles
in the same way we should divide 120 to 60 to find the needed time to cover 120 miles ,so t= 2 hours
so the total time for covering total distance would be 3+2 = 5 hours and total distance is 60+120= 180 miles
Final stage : average speed is total distance divide to total time : 180/5 = 36 miles per hour....