S2 Maths Revision Plsss Help Mee!!!:(

the number of hits on a website is recorded. over a long period of time the mean number of hits per hour is 6.9

explain briefly why the number of hits per unit time could be modelled by a poisson distribution

assuming a poisson model, calculate the probability that the website has
exactly 6 hits in an hour
exactly 3 hits in each of two successive 30 minute intervals

:confused:

i really need this answer i tried doing it but i dont get it because my teachers a idiot. thanks

Reply 1

Glockity

11

10 Years, hope your living a good life!!

For part 1, since it is a rate ie number over a time it can be infinite and therefore be modelled as Poisson. Also we can assume mean and variance are approximately equal.

For part 2:

P ~ Po (6.9) P(X=6) = 01.511

then

We need 30 minute intervals so new mean is 6.9/2 = 3.45

so

P ~ Po (3.45) P(X=3) = 0.2173

since it is two successive we can think of a tree diagram and so for the two hits we multiply the answer by itself.

so

0.2173 squared = 0.0472

P.S. I have a Classwiz calculator so I just used the Poisson function however you can also calculate it the same way with the equation.

Reply 2

kaci_a

3

Original post by Glockity

10 Years, hope your living a good life!!

For part 1, since it is a rate ie number over a time it can be infinite and therefore be modelled as Poisson. Also we can assume mean and variance are approximately equal.

For part 2:

P ~ Po (6.9) P(X=6) = 01.511

then

We need 30 minute intervals so new mean is 6.9/2 = 3.45

so

P ~ Po (3.45) P(X=3) = 0.2173

since it is two successive we can think of a tree diagram and so for the two hits we multiply the answer by itself.

so

0.2173 squared = 0.0472

P.S. I have a Classwiz calculator so I just used the Poisson function however you can also calculate it the same way with the equation.