Question

QUICK PLS HELP

The mean number of typhoon hitting US follows a Poisson distribution with
variance 0.5 per month. Find the probability that
(a) 4 typhoons will hit US in a year.
(b) at least 2 typhoons will hit US in a given half-year.

Answer 1

A) 0.1339

B) 0.8078

Explanation:

The Poisson Distribution formula is given by;

P(x; μ) = (e^(-μ) × (μ^(x))/x!

We are given;

Variance = 0.5 per month

Now, in Poisson distribution, variance = mean.. Thus, mean μ = 0.5 per month

A) We want to find the probability that 4 typhoons will hit US in a year.

Thus, x = 4

But since it's for a year, then μ = 0.5 × 12 = 6

So;

P(x = 4) = (e^(-6) × (6^(4))/4!

P(x = 4) = 0.00247875 × 1296/24

P(X = 4) = 0.1339

B) probability that at least 2 typhoons will hit US in a given half-year is;

P(X ≥ 2) = 1 - P(X < 2)

P(X < 2) = P(X = 0) + P(X = 1)

In a half given year, μ = 0.5 × 6 = 3

P(X = 0) = (e^(-3) × (6^(0))/0!

P(X = 0) = 0.0498

P(X = 1) = (e^(-3) × (6^(1))/1!

P(X = 1) = 0.1494

P(X < 2) = 0.0498 + 0.1494

P(X < 2) = 0.1922

P(X ≥ 2) = 1 - 0.1922

P(X ≥ 2) = 0.8078