You are Here: Home >< Maths

# Statistics 2 (edexcel) poisson dist. question Watch

1. Hi, I was just wondering, if they give you Po(x) for the rate of something happening in a day, and then they ask you to find the p of it happening over a week, would you do Po(7x)?
I ask this because the above is what i have been doing, however, in the exam style paper in the back of the book (question 4) they keep Po(3) - rate for 1 day, but just multiply it by 100 at the end (to find the p of it happening over 100 days).
Isn't that incorrect? on example 6 page 25 (section 2.4) they clearly multiply the mean by 2 which is the change in the period of days.

Atofu
2. I'd assume you're referring to parts b,c, and d of that question.

For b, you find P(X=0). Then the question is asking for the expected number of days out of 100 when X=0. So just do 100P(X=0). Similar for the rest.
3. (Original post by valhalla92)
I'd assume you're referring to parts b,c, and d of that question.

For b, you find P(X=0). Then the question is asking for the expected number of days out of 100 when X=0. So just do 100P(X=0). Similar for the rest.
ah okay, so if they asked for the probability out of 100 days, that's when you would multiply the mean by 100? but if they ask you for the number of days, you just calculate the probability for 1 day and multiply by 100?
4. (Original post by atofu)
ah okay, so if they asked for the probability out of 100 days, that's when you would multiply the mean by 100? but if they ask you for the number of days, you just calculate the probability for 1 day and multiply by 100?
Yes - the question wants how many vans for 100 one day periods.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 30, 2010
Today on TSR

### Oxford grad sues for £1m

Claims damages because he didn't get a first

### 'No evidence of shots fired' at Oxford Circus

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.