$A$ car starts from rest and moves such that it possesses average speeds of $5 \, ms^{-1}$,$10 \, ms^{-1}$,and $15 \, ms^{-1}$ in the first,second,and third seconds,respectively. What is the total distance covered by the car in these three seconds? ......... $m$

$A$ particle covers half of its total distance with speed $v_1$ and the rest half distance with speed $v_2$. Its average speed during the complete journey is

$A$ train has a speed of $60\, km/h$ for the first one hour and $40\, km/h$ for the next half hour. Its average speed in $km/h$ is

$A$ car covers distance $AB$ with the first one-third at velocity $v_{1} \, ms^{-1}$,the second one-third at $v_{2} \, ms^{-1}$,and the last one-third at $v_{3} \, ms^{-1}$. If $v_{3}=3v_{1}$,$v_{2}=2v_{1}$,and $v_{1}=11 \, ms^{-1}$,then the average velocity of the car is . . . . . . $ms^{-1}$.

$A$ body covers the first one-third of the distance with a velocity of $20 \, m/s$,the second one-third with a velocity of $30 \, m/s$,and the last one-third with a velocity of $40 \, m/s$. The average velocity is nearly........$m/s$.

$A$ car travels half the distance with a constant velocity of $40 \, km/h$ and the remaining half with a constant velocity of $60 \, km/h$. The average velocity of the car in $km/h$ is