119k views
1 vote
How do you do these questions? The same distributional assumptions will be made. This article from the Guardian in 2015 reports on two shark attacks in two days.

How do you do these questions? The same distributional assumptions will be made. This-example-1
How do you do these questions? The same distributional assumptions will be made. This-example-1
How do you do these questions? The same distributional assumptions will be made. This-example-2

1 Answer

3 votes

Explanation:

October 4th is the 277th day of the year, so the average number of shark attacks in 2015 in a two-day period is:

29 / 277 × 2 = 0.21

The probability of 2 attacks in a two-day period is:

P(x; μ) = e^(-μ) (μˣ) / x!

P(2; 0.21) = e^(-0.21) (0.21²) / 2!

P(2; 0.21) = 0.0178

The probability of at least 2 attacks is:

P(≥2; 0.21) = 1 − P(0; 0.21) − P(1; 0.21)

P(≥2; 0.21) = 1 − e^(-0.21) (0.21⁰) / 0! − e^(-0.21) (0.21¹) / 1!

P(≥2; 0.21) = 0.0186

User Sallyhornet
by
7.1k points