On a highway, a car is driven 80. kilometers
during the first 1.00 hour of travel,
50. kilometers during the next 0.50 hour, and
40. kilometers in the final 0.50 hour. what is the
car’s average speed for the entire trip?
(1) 45 km/h (3) 85 km/h
(2) 60. km/h (4) 170 km/h

The average speed of the car for the entire trip can be calculate by using:

where S is the total distance covered by the car, and t is the total time taken.

The total distance travelled by the car is:

while the total time taken is:

so, the average speed of the car is:

so, the correct answer is (3) 85 km/h.

b) 10 minutes

girls stopped for 10 minutes.