A garden water butt holds 180 litres when full. It is currently 3/5 full.
(a)Calculate the number of litres currently in the water butt.(2)
(b)The tap on the water butt drains water at a constant rate of 3 litres per minute, but light rain refills it at the same time, at a rate of 0.6 litres per minute. Calculate the net rate at which the water level falls, in litres per minute.(1)
(c)Calculate how long it will take, in minutes, for the water butt to empty completely at this net rate.(2)
(Total for Question 23 is 5 marks)