- The following information is known about a consumer electronics store: The number of people who make some type of purchase follows a Poisson distribution with a mean of 100 per day. • The number of televisions bought by a purchasing customer follows a Negative Binomial distribution with parameters r= 1.1 and = 1. Using the normal approximation, calculate the minimum number of televisions the store must have in inventory at the beginning of each day to ensure that the probability of its inventory being depleted during the day is 1.0%.