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Abdul, while driving to school, computes the average speed forhis trip to be 20 km h-?. On his return trip along the sameroute, there is less traffic and the average speed is30 km h . What is the average speed for Abdul's trip? |
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Answer» Let the dist. be xdist. while going = dist while returningtime = dist./speedso, time while going = x/20time while coming =x/30total time= x/20+x/30=(3x+2x)/60=5x/60=x/12total dist.= 2xavg. speed = total dist./total speed=2x*12/x=24km/hr given , speed of car =20,30km/hraverage speed =totaldistance/time takentime =2hr because 20km per hour ,30 km per hour both are hoursboth time =1+1=2average speed =20+30/2=50/2=25km/hr |
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