The demand for water use in Phoenix in 2003 hit a high of about 442 million gallons per day on June 27,2003. Water use in the summer is normally distributed with a mean of 310 million gallons per day and a standard deviation of 45 million gallons per day. City reservoirs have a combined storage capacity of nearly 350million gallons.
a) What is the probability that a day requires more water thanis stored in city reservoirs?
b) What reservoir capacity is needed so that the probability it is exceeded by 1%?
c) What amount of water use is exceeded with 95%probability?
d) Water is provided to approximately 1.4 million people. What is the mean daily consumption per person at which the probability that the demand exceeds the current reservoir capacity is 1%? Assume that the standard deviation of demand remains the same.