You need to make 5 grilled cheese sandwiches. You have a grill that is large enough to toast 2 sandwiches at a time. The sandwiches must be toasted one minute on each side. It takes 3 seconds to flip a sandwich and 5 seconds to take one off or put one on the grill. What is the shortest amount of time needed to toast all five sandwiches?

Each sandwich is toasted for 2 minutes and it takes 3 seconds to flip it.

The first two sandwiches will be toasted in 2 minutes (toasting) and 6 seconds (flipping).

The two will then be switched which will take 10 seconds.

The next two will again take 2 minutes and 6 seconds.

The final sandwich will take 5 seconds to be placed.

The final sandwich will also take 2 minutes to toast and 3 seconds to flip.

Total time:

2 + 2 + 2 = 6 minutes

6 + 10 + 6 + 3 = 25 seconds

Total time is 6 minutes and 25 seconds.

2 sandwiches -

4 minutes to toast

6 seconds to flip

20 seconds to take off or put on

4 minutes and 26 seconds

4 sandwiches

8 minutes and 52 seconds

last sandwich

2 minutes to toast

3 seconds to flip

10 seconds to take off or put on

2 minutes and 13 seconds

total: 10 minutes 65

11 minutes and 5 seconds