Answer :
40 km\h
d1=15km s1=30km\h
d2=10km s2=20km\h
d3=75km s3=50km\h
total time taken=t1+t2+t3
=0.5+0.5+1.5=2.5
speed =distance\time
100\2.5=40km\h
d1=15km s1=30km\h
d2=10km s2=20km\h
d3=75km s3=50km\h
total time taken=t1+t2+t3
=0.5+0.5+1.5=2.5
speed =distance\time
100\2.5=40km\h
D1=15km
D2=75km
D3=10km
S1=30kmh-1
S2=50kmh-1
S3=10kmh-1
Avg. Speed=total distance÷total time taken
T1=0.5hr
T2=0.67hr
T3=0.5hr
Let the avg.speed be s.
S=15+75+10÷0.5+0.5+0.67
S=100÷1.67
Therefore,s=40kmperhr