A naturalist leads whale watch trips every morning in March

A naturalist leads whale watch trips every morning in March. The number of whales seen has a Poisson distribution with a mean of 4.3. Find the probability that on a randomly selected trip, the number of whales seen is 3.

A) 0.3057 B) 0.1798 C) 0.5394 D) 0.3596

Solution

Possion Distribution
PMF of P.D is = f ( k ) = e- x / x!
Where   
= parameter of the distribution.
x = is the number of independent trials
P( X = 3 ) = e ^-4.3 * 4.3^3 / 3! = 0.1798