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**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

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

60 km in 40 min= 60/40

n km in 1 hour =n/60

60/40=n/60

=90km/1 hour

n km in 1 hour =n/60

60/40=n/60

=90km/1 hour