Question 1189155
.
<pre>


I extended the table, adding the columns with average petrol sales from each group of stations

and total sales from each of groups of stations.


         T          a          b          l          e


Amount of petrol (P L) Frequency   Average of petrol sales    Estimate of petrol sales 
                                   from these stations        from these stations
  2000 to 3000            4              2500                      2500*4
  3000 to 4000            4              3500                      3500*4
  4000 to 5000            9              4500                      4500*9
  5000 to 6000           14              5500                      5500*14
  6000 to 7000           23              6500                      6500*23
  7000 to 8000           16              7500                      7500*16


Then I calculated a gross total estimation.


Gross total estimation = 2500*4 + 3500*4 + 4500*9 + 5500*14 + 6500*23 + 7500*16 = 411000 L = 411 kL.    <U>ANSWER</U>
</pre>

Solved (and explained).