Question

17. A car moves with a speed of 30 km/h for half an hour, 25 km/h for one hour and 40 km/h for two hours. Calcualate the average speed of the car.

Answer 1

Answer:

120km/h

Step-by-step explanation:

half of 30=15

25km/h for one hour

40km/h for two hour

answer=120km/h

Answer 2

$\bf{\underline{\underline{\bigstar\bigstar\: Solution : }}}$

$\:\:$

$\rule{200}3[/tex</p><p></p><p>[tex]\:\:$

$\footnotesize{ Speed = \dfrac{distance}{time} }$

$\footnotesize{\implies Speed \times Time = distance }$

$\footnotesize{\implies 30km/h \times \dfrac{1}{2} hour = distance }$

$\footnotesize{\implies 15km = distance }$

$\:\:$

$\rule{200}3[/tex</p><p></p><p>[tex]\:\:$

$\footnotesize{ Speed = \dfrac{distance}{time} }$

$\footnotesize{\implies Speed \times Time = distance }$

$\footnotesize{\implies 25km/h \times 1hour = distance }$

$\footnotesize{\implies 25km = distance }$

$\:\:$

$\rule{200}3[/tex</p><p></p><p>[tex]\:\:$

$\footnotesize{ Speed = \dfrac{distance}{time} }$

$\footnotesize{\implies Speed \times Time = distance }$

$\footnotesize{\implies 40km/h \times 2hours = distance }$

$\footnotesize{\implies 80km/h = distance }$

$\:\:$

$\rule{200}3$

$\:\:$

$\footnotesize{ Average \: Speed = \dfrac{total \: distance}{total \: time} }$

$\footnotesize{\implies Average \: Speed = \dfrac{15km + 25km + 80km}{\dfrac{1}{2} hours + 1 hours + 2 hours} }$

$\footnotesize{\implies Average \: Speed = \dfrac{15km + 25km + 80km}{\dfrac{1 + 2 + 4 }{2} hours} }$

$\footnotesize{\implies Average \: Speed = \dfrac{120km}{\dfrac{7}{2} hours} }$

$\footnotesize{\implies Average \: Speed = \dfrac{120km}{3.5 hours} }$

$\footnotesize{\implies Average \: Speed = 34.28km/h }$