The average Belfast household uses 14,000 litres of water per week, with a standard deviation of 3,000 litres. Assume a normal distribution.

i. What proportion of Belfast households use less than 14,000 litres of water per week?

ii. What proportion of Belfast households use less than 8,000 litres of water per week?

iii. What proportion of Belfast households use between 8,000 and 12,000 litres of water per week?