A factory worker at a t-shirt factory prints logos on each newly made t-shirt one after the other. Let T_k be the length of time he takes to print the logo on the kth t-shirt. For 300 t-shirts assume that these random variables are independent and identically distributed with a common mean of 2 minutes and a standard deviation of 30 seconds. Use the normal approximation to calculate the probability that his job takes at least 9 hours and 45 minutes, but no more than 10 hours and 15 minutes.