Production the rate of production of a new line of products is given by
dx/dt = 200[1+{400/(t+40)2}]
where x is the number of items and t is the number of weeks the product has been in production.
(a) Assuming that x = 0 when t = 0, find the total number of items produced as a function of time t.
(b) How many items were produced in the fifth week?