a cement company sells his production in different cities through the appointed dealers. the sales of his production in the last year is given in the following tabular form: sales (in '00' bags) 0-500 500-1000 1000 0-50-500-100/100 - 0-15001500-20002000-2500 number of dealers 40 48 60 52 35 2500 and more 22​