Health Canada has established a new maximum allowable concentra- tion for lead in drinking water of 5 ppb. Assume that the amount of lead contained in the water of a house built in Ottawa before 1950 is normally distributed with mean 3.5 ppb and standard deviation 1.5. What is the probability that a randomly chosen house in Ottawa, which was built before 1950, exceeds the maximum allowable concen- tration for lead in water ?

A) 0.1677 ; B) 0.1487 ; C) 0.9413 ; D) 0.8413 ; E) 0.1587 ;