Question

a car covers a distance of 60 km in 40 minutes find the speed of car in km/h

Answer 1

speed = distance /time
1)time = 40 min = 40/60 hour
        = 2/3 hour
∴speed = 60/(2/3)
             =(60×3)/2
             = 90 km/hour
to change into m/s
90 km/hour = (90×1000)/3600
                    =25 m/s
2) distance = 800 m = 0.8 km
time = 30 min = 30/60 = 0.5 hour
speed = 0.8/0.5 = 1.6 km/hour
3)distance = 16 km = 16000 m
time = 4/3 hour =( 4/3)×3600 = 4800 sec
speed = 16/(4/3) = 12 km/hour
 or , speed = 16000/4800 = 3.33 m/s
4) distance = (50/60)×42 = 35 km

2- 4 questions are from the picture

Answer 2

60 km in 40 min= 60/40
n km in 1 hour =n/60
60/40=n/60
=90km/1 hour