Thank you for looking through this problem, much appreciated! I tried to work out the answer for a, but I got .2946 when the actual answer is .3085... How do I start this? By the way, I just want to take the time to genuinely thank all the people that answer questions here, you are life savers, and I give partial credit to the grade I get on my next exam to you.
"Suppose that the length of life in hours of a light bulb manufactured by company A is N(800, 14400) and the length of life in hours of a light bulb manufactured by company B is N(850, 2500). One bulb is randomly from each company and is burned until "death".
a.) Find the probability that the length of life of the bulb from company A exceeds the length of life of the bulb from company B by at least 15 hours.
b.) Find the probability that at least one of the bulbs "lives" for at least 920 hours."