Show all work Assume the Probability distribution of the lifespan for light bulb X is normal with a mean 900 hours and variance 10,000 Assume the Probability distribution of the lifespan for light bulb Y is normal with a mean 1000 hours and variance 40,000 7. Compute the 80th percentile for the lifespan for X light bulbs 8. Which light bulb x or y would you prefer if you wanted one with the highest probability of lasting more than 750 hours 9. The manufacturer of light bulb X wishes tp advertise that 90% of light bulbs last more than k hours. Find k The distribution of the daily demand for milk in a given area is normally distributed with mean 3000 gallons and standard deviation 250 gallons. 1. Compute the probability that the demand in a randomly selected day is between 2800 gallons and 3200 gallons. 2. On what percentage of days does the demand for milk exceed 2500 gallons? 3. A supplier of milk wishes to order sufficient quantity so as to be 90% certain that he alone will be able to meet the demand for a given day. How many gallons of milk should be ordered