Question

A person covers half of the total distance at the speed of 40 km per hour, half of the remaining at 20 km per hour and the rest at 10 km per hour. Find the average speed during the journey.​

Answer 1

average speed= total distance/total time taken

Step-by-step explanation:

• let us assume that the total distance as a.
• 1st half distance i.e. for a/2 time taken = t1 and speed =40km/hr.
• therefore t1=a/80.
• similarly next half of the remaining distance with 20km/h and time t2
• t2=a/4*1/20=a/80.
• similarly the remaining distance a/4 with 10km/h and time taken is t3
• t3=a/4*1/10=a/40.
• total time=t1+t2+t3=a/80+a/80+a/40=2a/80+a/40=2a/40=a/40
• avg speed= total distance/total time taken=a/(a/40)=40km/hr