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**MathGeek06** In terms of Poisson and Binomial distributions, what is the complement of:

* At least half

* More than

1. Customers returning items to a store arrive at the customer service desk according to a Poisson process with arrival rate of 18 per 30 minute interval. The probability that an arriving person is extremely upset is 50%. What is the chance that **more than 100** extremely upset customers arrived between 7 and 8 pm?

2. Now suppose that exactly 30 customers arrived in the first half hour of operations. What is the probability that **at least half** of them are extremely upset?

I know I have to rewrite these in terms of complements, but I'm not quite sure how.