Lengths of the pool

This resource is about solving maths problems around swimming training.

Susan swam 25 lengths of a swimming pool at a steady rate, had a 10 minute rest, then swam 15 more lengths at the same speed. In total, this took exactly half an hour.
 

a) How many lengths did Susan swim? __________
 
b) How long was she swimming for? __________
 
c) How long did Susan take to swim 1 length? __________
 
d) How long did Susan take to swim the first 25 lengths of the pool? __________
 
e)
If Susan swam at the same steady speed, how long would 100 lengths of the pool take her? 
 
__________
 
f)
How many lengths of the pool would Susan cover in 10 minutes if she swam 5 lengths every 2 minutes? 
 
__________