Problems

There is a 12 litre barrel filled with water, and two empty barrels (one is 5 litres in volume and the other is 8 litres). Using these barrels, try to

a) divide the water into 2 parts with volumes: 3 litres and 9 litres;

b) divide the water into 2 parts with equal volume.

A candle that burns out completely in one hour costs $60$ pence and a candle that lasts for $11$ minutes costs $11$ pence. For some reasons which he doesn’t want to explain to the seller, Mr. Fawkes wants to measure exactly $1$ minute with some of these candles. Can he manage to do that if he has only $1$ pound and $50$ pence to spend on the candles?
Mr. Fawkes can only measure the whole interval with each of the candles. He is not guaranteed that any of the candles burns uniformly, so he cannot divide it into two parts. He cannot make it burn faster by igniting them from both ends, but he can extinguish a candle and light it up again later.