Under what condition is the average velocity $($which is defined to be the total displacement divided by the time$)$ equal to the average of the initial and final velocities, $\backslash (\backslash$left$($v$\_\{\backslash$mathrm$\{$i$\}\}+$v$\_\{\backslash$mathrm$\{$f$\}\}\backslash$right$)/2\backslash )?$

The acceleration must be constant

It is true for other motions besides constant acceleration, but not for all possible motions

It is true for all possible motions.

The velocity must be constant

none of the above

Two cars, with initial speeds of $\backslash (2$ v $\backslash )$ and $\backslash ($ v $\backslash ),$ lock their brakes and skid to a stop. Assume that the deceleration while skidding is independent of the speed. The ratio of the distances traveled is

$1$

$2$

$4$

$8$

$16$