As increases, say, to values greater than 30, the Poisson distribution begins to be very similar

As μ increases, say, to values greater than 30, the Poisson distribution begins to be very similar to the normal with both a mean and variance of μ. Using this approximation, determine how many telephone operators are needed to ensure at most 5% busy signals if the mean number of phone calls at any given time is 30.

 LO.1