Knowing how to do it in matlab is only a small part of solving this problem. You should first follow the given hint - the number of bacteria doubles every 40 minutes. Use this to determine what the value k is. Suppose you decide that a minute will be your fundamental unit of time. Then you should ask yourself this question: if we start with one bacterium and forty minutes later we have two of them, the equation would have to be:
2 = 1*exp(k*40)
Now what value must k have to satisfy this equation? I will give you one further hint. If two sides of an equation are equal, then so are their logarithms! The rest is up to you, Astuream.
