Average speed = distance travelled / time.
( note: distance must be in (m) and time in sec, if not then you convert ).
1) average speed = 20/2 = 10mls.
2) average speed = 100/5 = 20 m/s.
3) since we aren't given (time) let's call it x
so we replace the unknown time with x..
average speed = 2/x = 1
then cross multiply
you get x (the unknown time) as 2s {seconds}.
(to check if it's correct just add the time we got back into the equation and see if you would get a erage speed as 1m/s).
4) do the same, replace distance as x or any letter you want )
average speed = x/ 10 = 50
cross multiply
you get x = 500m {meters}
5) (we need to convert km to meters and time to secs because that's what we are working with).
200km = 200,000 m { to convert to meters you multiply the given by 1000, 1km = 1000m).
for 2h, we know that:
60 seconds makes 1 minute
60 minutes makes an hour.
so we multiply 60 by 60 we get 3600mins then we multiply it by 2 to get 7200 secs
so now
Average speed = 200,000/7200 = 27.77 m/s.
Here you go..
hope this helps
Good luck and ace that test.