A heater uses \(30.7p\) of electricity each hour. If the heater is switched on for 4 hours and 15 minutes, what will be the cost of the electricity used?
First convert the time to decimal time.
4 hours and 15 minutes is \(4.25\,hours\).
Cost of electricity \(= 30.7p \times 4.25 = 130.475p = \pounds1.30 \)(to the nearest penny)
Question
To achieve a required colour, dye is to be added to white paint.
The proportion of dye to be added is \(2.3\,ml\) for \(1\,litre\) of white paint.
How much dye needs to be added to a \(5\,litre\) tin of white paint?
Amount of dye required \(= 2.3 \times 5 = 11.5\,ml.\)