a person while.driving to office compute the average speed for his tri

1.	a person while.driving to office compute the average speed for his trip to be 70 km/h on his return trip along the same route there is less traffic and average speed is 50km/h what is average speed of persons trip
Answer» Answer: GIVEN : Method I: Let the distance traveled by Abdul from HOME to school = s km time taken to reach the school=t1 sec For Return JOURNEY , Abdul cover distance =s km time=t2 sec ∴ Average speed for forward journey[home - school ] = Total distance/ Total time. 20 km/h =s/t1 ∴t1=s/20 h ------eq(1) Average speed for backward journey[school -home] = Total distance/ Total time. 30 km/h =s/t2 t2=s/30h -----eq(2) Average distance for entire journey = Total distance/ Total time =(s+s)/[s/20 +s/30] =2s/s[1/20+1/30] =2x20x30/50 =24 km/hr Shortcut method : If equal distance are covered with speeds v1 and v2 then average distance=2v1v2/v1+v2 = 2x20x30/50 =24km/hr ∴ The average speed for persons trip is 24km/h

a person while.driving to office compute the average speed for his trip to be 70 km/h on his return trip along the same route there is less traffic and average speed is 50km/h what is average speed of persons trip

Answer»

Answer:

GIVEN :

Method I:

Let the distance traveled by Abdul from HOME to school = s km

time taken to reach the school=t1 sec

For Return JOURNEY , Abdul cover distance =s km

time=t2 sec

∴ Average speed for forward journey[home - school ] = Total distance/ Total time.

20 km/h =s/t1

∴t1=s/20 h ------eq(1)

Average speed for backward journey[school -home] = Total distance/ Total time.

30 km/h =s/t2

t2=s/30h -----eq(2)

Average distance for entire journey = Total distance/ Total time

=(s+s)/[s/20 +s/30]

=2s/s[1/20+1/30]

=2x20x30/50

=24 km/hr

Shortcut method : If equal distance are covered with speeds v1 and v2 then average distance=2v1v2/v1+v2

= 2x20x30/50

=24km/hr

∴ The average speed for persons trip is 24km/h