Start with both the hourglasses. When 11 minute's finishes, stop both of them. then turn the 11 minute's hourglass. and start the 13 minute's hourglass. this will give us the 2 minutes in 11 minute's time in that hourglass. and using this we can measure 15 MINUTES.

? + ? + ? + ? + ? = 30

You have to fill numbers in place of question marks. The numbers that you can use are 1, 3, 5, 7, 9, 11, 13 and 15. You can repeat the numbers if you like.

I possess two wires. Both of them have an inconstant thickness but both of them burns completely in sixty minutes. The problem is that I want to measure forty-five minutes while using these two wires.

How can I measure if cutting the wire in half is not possible due to non-homogeneous construction ?