You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h.Your average speed over the 12 km drive will be
A)greater than 70 km/h.
B)equal to 70 km/h.
C)less than 70 km/h.
D)exactly 38 km/h.
E)It cannot be determined from the information given because we must also know directions traveled.

Question

Quizplus · Accepted Answer

Average speed is calculated as total distance traveled divided by total time taken. In this case, the total distance traveled is 12 km and the time taken can be calculated as follows:

Time taken for the first 6 km = Distance/Speed = 6/50 = 0.12 hours
Time taken for the next 6 km = Distance/Speed = 6/90 = 0.067 hours
Total time taken = 0.12 + 0.067 = 0.187 hours

Average speed = Total distance/Total time = 12/0.187 = 64.17 km/h

Therefore, the average speed over the 12 km drive will be less than 70 km/h.

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