The puzzle asks for measuring time with the use of ropes. Its as follows
You have two identical ropes that are non-uniform in composition. You only know one useful property of the ropes i.e. "They burn completely in 1 hour."
Now you only have a lighter and those two ropes and you've got to tell when 45 minutes have elapsed.
That means you have to measure 45 minutes using those to ropes and the lighter
So work out....
Further how many ropes will be required to measure 10 minutes!!!