a car moves 1/3 distance with speed 20km/hr and 2/3 with 60km/hr .average speed?
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let the total distance be x km.
Vavg=Δd/Δt
let v be speed for first 1/3 distance and V be speed for 2/3 distance.
v=d/t
20=(x/3)/t
20=x/3t
3t=x/20
t=x/60.
V=d/t
60=(2x/3)/t
3t=2x/60
t=2x/60×3
t=x/90
As Vavg=Δd/Δt
Vavg=x/(x/90+x/60)
Vavg=x/{(2x+3x)/180}
Vavg=x/(5x/180)
Vavg=x/(x/36)
Vavg=36x/x
Vavg=36 km/h
Therefore Vavg is=36 km/h
Vavg=Δd/Δt
let v be speed for first 1/3 distance and V be speed for 2/3 distance.
v=d/t
20=(x/3)/t
20=x/3t
3t=x/20
t=x/60.
V=d/t
60=(2x/3)/t
3t=2x/60
t=2x/60×3
t=x/90
As Vavg=Δd/Δt
Vavg=x/(x/90+x/60)
Vavg=x/{(2x+3x)/180}
Vavg=x/(5x/180)
Vavg=x/(x/36)
Vavg=36x/x
Vavg=36 km/h
Therefore Vavg is=36 km/h
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