Jawab:

An average of 2 per week means that the agent on average sells 8 houses per month (per 4 weeks). Therefore, we are going to compare the probability of the agent selling more than 6 houses per month given the average of 8 per month (λ = 8).

P(x = k) = λ^k × e^(-λ) ÷ k!

P(x = 0) = 8^0 × e^(-8) ÷ 0!

P(x = 1)  = 8^1 × e^(-8) ÷ 1!

P(x > 6) = 1 - P(x ≤ 6)

P(x > 6) = 1 - [P(x = 0) + P(x = 1) + P(x = 2) + P(x = 3) + P(x = 4) + P(x = 5) + P(x = 6)]

P(x > 6) = 1 -  P(x <= 6)

P(x > 6) = 1 - 0.31337

P(x > 6) = 0.68663