World's Shortest Intelligence Test

It's called the Cognitive Reflection Test (CRT). Here are the questions:

1) A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?

2) If it takes 5 machines 5 min to make 5 widgets, how long would it take 100 machines to make 100 widgets?

3) In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of the lake?

Don't look until you come up with your answers, but the answer to #1 and #2 are on the ball in the picture to the right.

Check out the link above for more information on this interesting test . . . and the answer to question #3.