4 A recycling firm collects aluminium cans from a number of sites. It crushes them and then sells the aluminium back to a manufacturer.
The profit from processing t tonnes of cans each week is , where
.
By completing the square, find the greatest profit the firm can make each week, and
how many tonnes of cans it has to collect and crush each week to achieve this profit.

Ascientist places 24 cells in a petri dish. she knows the cells grow at an exponential rate, doubling in number every hour. how long will it take (in hours) for there to be 1100 cells in the dish? time to 1100 cells: 5.51832530 hours how long will it take to reach 110 cells? time to 110 cells : 2.1963972 hours what is the average rate of change in the number of cells between 9 hours and 11 hours? average rate of change: cells per hour what is the instantaneous rate of change after 7 hours? instantaneous rate of change: cells per hour note: you can earn partial credit on this problem.