1.   11 steps

    

2.   a) round covers cannot fall through the round hole accidentally.

      b) heavy covers can be rolled into position.

      c) round covers can cover holes no matter how they are orientated.

      

3.   Sunday

      

4.   65 minutes

      

5.   30 years old

      

6.   Neither

      

7.   10

      

8.   11.00pm

      

9.   Left

    

10. 45 minutes

      (after 30 minutes the tank is 2/3 full so 1/3 = 15 mins & full tank = 45 mins)