SOLUTION
Question 4
4.1 From the question, the normal charge of electricity excluding VAT for 0 - 50 range was 0.6340. The price including VAT in the table was calculated as

4.2
If SIzwe used 222 kWh of electricity, the range of this from the table fall under >50 - 350, and the charge for that is 1.0804
Hence the answer is 1.0804
4.3
The graph is shown below