Question 1209708
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In the three months of May, June, and July, water usage was 4500-4000 = 500 litres over the average each month making a total of 3*500 = 1500 litres over the average.<br>
For the overall average for the whole year to be 4000 litres per month, the total consumption in the other 9 months must be 1500 litres under the average.<br>
1500 litres under the average, distributed evenly over the 9 months, means monthly consumption is 1500/9 = 500/3 = 166 2/3 liters under the monthly average of 4000 litres.<br>
ANSWER: 4000 - 166 2/3 = 3833 1/3 litres per month<br>