The answer to last week's brainteaser was posted in the comments section. This week, burning rope:

There are two lengths of rope.
Each one can burn in exactly one hour.
They are not necessarily of the same length or width as each other.
They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.

By burning the ropes, how do you measure exactly 45 minutes worth of time?

ANSWER: The answer is posted below in white text. Highlight the area to see it.

Simultaneously light rope #1 on both ends and rope #2 on just one end. The burning ends of rope #1 will meet in the middle in exactly 30 minutes. At this point, rope #2 has 30 minutes of burn left. Light the second end of rope #2 to cut that to 15 minutes.