$A$ car travels a distance $S$ on a straight road in two hours and then returns to the starting point in the next three hours. Its average velocity is

$A$ car covers $2/5^{th}$ of the total distance with speed $v_1$ and $3/5^{th}$ of the total distance with speed $v_2$. What is its average speed?

Explain average velocity and average speed.

If a car travels $40 \%$ of the total distance with a speed $v_1$ and the remaining distance with a speed $v_2$,then the average speed of the car is:

$A$ person walks along a straight road from his house to a market $2.5 \,km$ away with a speed of $5 \,km/h$ and instantly turns back and reaches his house with a speed of $7.5 \,km/h$. The average speed of the person during the time interval $0$ to $50 \,min$ is (in $m/s$)

Which among average speed and average velocity can be positive,negative or zero?