Find \sin\left(\dfrac{7\pi}{12}\right)si n( 12 7π )sine, (, start fraction, 7, pi, divided by, 12, end fraction, )exactly using an angle addition or subtraction formula.'

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?