Question

Abdul ehild driving to school computes the average speed for his trip to he 20km/h on his return trip along the same route their is less traffic and the average speed is 40km/h what is the average speed for abdul trip

Answer 1

case 1
speed for the first case =20km/hr
since the dis for both the cases are same so let us consider dis =d
let time for case 1 =t1
now ,t1=d/s=d/20


case 2
speed=40km/hr
dis=d
time =t2=d/40

so total time = d/20+d40
3d/40
to find avg speed =total dis/total time
= 2d/3d/40
= 2d×40/3d
=80/3


answer =80/3 km/hr
hope it helps

Answer 2

$\textbf{\underline{\underline{According\:to\:the\:Question}}}$

$\huge{Assume\:distance\: to\: school \:be\: p km.}$

→Then time taken to drive school will be

$\tt{\rightarrow\dfrac{p\:km}{20km/hour}}$

$\tt{\rightarrow\dfrac{p}{20}hour}$

★Now

$\textbf{\boxed{Next\;situation}}$

Time taken to return from the journey :-

$\tt{\rightarrow\dfrac{p\:km}{40km/hour}}$

$\tt{\rightarrow\dfrac{p}{40}hour}$

★Hence

→Total distance travelled :-

= p km + p km

= 2p km

★Now

→Total time taken :-

$\tt{\rightarrow\dfrac{p}{20}hour+ \dfrac{p}{40}hours}$

$\tt{\rightarrow\dfrac{3p}{40}}$

★Then

→Average speed for whole trip :-

$\tt{\rightarrow\dfrac{2p}{3d/40}}$

${\rightarrow\dfrac{2p\times 40}{3d}km/hour}$

= 26.7 km/h

$\because{\boxed{We get}}$

→Average speed for whole trip is 26.7 km/hour