Question

1] a car covers the first half of the distance between two places at a speed of 40 km/h and the second half at 60 km/h .what is the average speed of the car2]a car goes from town A to another town B with a speed of 40 km/h and returns back to the town A with a speed of 60 km/h.calculate the average speed during the whole journey.3] a girl moves with a speed of 6 km/h for 2hrs and with the speed of 4km/h for the next 3hrs. Find the average speed of the girl and the total distance moved.

Answer 1

1-->
a car covers the first half of the distance between two places at a speed of
40km/hr and second half at 60 km/hr . calculate the average speed of the car
:
let a = average speed for the trip
let d = half the distance
:
write a time equation, time = dist/speed
 +  = 
we don't need d, divide thru by d and you have
 +  = 
multiply by 120a to clear the denominators, results:
3a + 2a = 120(2)
5a = 240
a = 240/5
a = 48 km/hr





2-->
a car goes from town A to another town B with a speed of 40km/hr and returns back to the same town at a speed of 60km/hr . calculate the average speed of the car
***
let x=distance between town A and town B

ave speed=distance/travel time=2x/travel time
travel time=distance/speed


ave speed=48 km/hr

3-->
Find the total distance, = 6*2 + 4*3, and divide by the total time, = 5 hours.