Answer:
He is incorrect! Her speed was 5m/s.
Explanation:
For calculating the speed, first we shall remember that:

Where
is the speed,
is the distance travelled and,
is the time it takes to travel distance
.
So one migth think that velocity can be easely compute:


Be carefull, he does not make a proper dimensional analisis!
Before computing the speed we must know in what dimensions our values are.
, distances is measure in Kilometers.
, time is measure in seconds.
If we want our speed to be in
, first we need to be sure that our values are expressed in meters and seconds.
Time is already expressed in seconds, distance is not in Kilometers.
So
,
now we can compute the speed:


