If A driver drives a car four times a lap 10,20 30,60 kmph.What is his average speed.

Editorial / Best Answer

Answered by: bhaskar s p

  • Jul 29th, 2005


avg speed for 2 speeds is 2*x*y/(x+y) 
therefore avg of 2*10*20/(10+20) and  
2*30*60/(30+60) which is equal to 20 
its correct 20

Showing Answers 1 - 21 of 21 Answers

suresh

  • May 26th, 2005
 

41.25Kmph

  Was this answer useful?  Yes

prashanth n

  • Jun 3rd, 2005
 

31.6 kmph (no camma given between 20 and 30 so 
4 times a lap totally 12 laps ,380 km)

  Was this answer useful?  Yes

SmartMan

  • Jun 5th, 2005
 

lap=x Km 
time for 1lap=x/10 h,2 lap=x/20 h,... 
all time = x/10+x/20+x/30+x/60=x/5 
average speed=4x/x/5=20 kmph

pradeepk

  • Jul 25th, 2005
 

30 kmph is correct bcoz 1st lap in 10 next 20 
etc.. total it 120 and divide it by no. of laps 
ie.120/4=30.

bhaskar s p

  • Jul 29th, 2005
 

avg speed for 2 speeds is 2*x*y/(x+y) 
therefore avg of 2*10*20/(10+20) and  
2*30*60/(30+60) which is equal to 20 
its correct 20

Raj

  • Aug 23rd, 2005
 

(4*10*20*30*40)/(10*20*30 +10*20*60 +10*30*60 + 20*30*60) =20

Abhishek

  • Sep 28th, 2005
 

(4*10+4*20+4*30+4*60)/16

=480/16

=30 kmph

  Was this answer useful?  Yes

Sheetal Salunkhe

  • Nov 23rd, 2005
 

1st lap 10kmph,2nd 20kmph, 3rd lap 60kmph

average=(10+20+30+60)/4=120/4=30kmph

average speed=30 kmph

  Was this answer useful?  Yes

Guest

  • Nov 24th, 2005
 

Avg Speed==Total Distance/Total Time

One lap=x Km 
Time for 1 lap=x/10 h,2 lap=x/20 h,... 


Total time = x/10+x/20+x/30+x/60=x/5 
Hence Average speed=4x/x/5=20 kmph

  Was this answer useful?  Yes

srilakshmi

  • Dec 30th, 2005
 

Ans is 25kmph......

Here goes the explanation:

distance for the 4 speeds is same i.e.,4 times a lap

let a lap=xkm

so distance=4x for all speeds

we need to find out the avg of 4 speeeds

since avg speed=(tot dist)/(tot time)

so find out tot time

t1=4x/10

t2=4x/20

t3=4x/30

t4=4x/40

tot dist=4x+4x+4x+4x=16x;

tot time=4x(1/10+1/20+1/30+1/40);

so avg speed=tot dist/tot time;

got it!!!

i.e.,avg speed=25kmph.....

  Was this answer useful?  Yes

jaspreet(jagz)

  • Feb 19th, 2006
 

av speed = total dist/toral time =4x /x(1/10+1/20+1/30+1/60 ) =4X(60/12) =20 ans

  Was this answer useful?  Yes

vamsi

  • Jun 19th, 2006
 

Avg Speed==Total Distance/Total Time

One lap=x Km 
Time for 1 lap=x/10 h,2 lap=x/20 h,... 


Total time = x/10+x/20+x/30+x/60=x/5 
Hence Average speed=4x/x/5=20 kmph

  Was this answer useful?  Yes

Amateur

  • Aug 7th, 2006
 

Number of laps will not matter as because speed is cosistent through out the lap.

30 is the correct answer. 

  Was this answer useful?  Yes

Jekin

  • Jun 30th, 2007
 

To sum up, the  ones  who believed it's 30 took an assumption that the driver drives the car in 4 different speeds for exactly the same time. But this is wrong! time = distance/speed.

  Was this answer useful?  Yes

microbes

  • Oct 31st, 2008
 

Answer = 30 KM / Hr

Avg Distance = Total distance / Total time

                      = (10 + 20 + 30 + 60) / 4 = 30 Km/Hr

 

 

  Was this answer useful?  Yes

Narendra Kulkarni

  • Sep 16th, 2011
 

4/(1/10+1/20+1/30+1/40) = 20 km/hr.

  Was this answer useful?  Yes

Give your answer:

If you think the above answer is not correct, Please select a reason and add your answer below.

 

Related Answered Questions

 

Related Open Questions