The drainage from a community during a storm is a normal random variable estimated to have a mean of 1.2 million gallons per day (mgd) and a standard deviation of 0.4 mgd.

The drainage from a community during a storm is a normal random variable estimated to have a mean of 1.2 million gallons per day (mgd) and a standard deviation of 0.4 mgd; i.e., N(1.2, 0.4) mgd. If the strorm drain system is designed with a maximum drainage capacity of 1.5 mgd, what is the underlying probability of flodding during a storm that is assumed in the design of the drainage system?