Modelling with the Poisson distribution (Edexcel IAL S2 2.2)

Pearson Edexcel IAL Statistics 2 Unit 2.2 Modelling with the Poisson distribution
Unit 2 The Poisson Distribution

00:00 Intro
02:00 Example 1
07:43 Example 2
13:05 Questions
13:41 Q1 Walkthrough
19:25 Q2 Walkthrough
24:31 Q3 Walkthrough
27:42 Q4 Walkthrough

[ammyt-dnep]

I wonder that the question at 26.42 why x less than or equal to n??

[kavaykapoor]

You missed out (b) in example 2. How would you do that?

[madelyn]

for anyone confused as to why its x less than or equal to n, in Q3 B), think of it like this. for example think n = 11 if you take x >(or equal to) 11 then we'll know we defiantly need more than 11 busses but we will not know how many we need, we'll know the minimum number we need (11) but what is the maximum number?? they're asking for the number of busses we need as in the maximum number needed.
if we find x <(or equal to) 11 we'll know that we need either 11 or a lesser number of busses. this gives us the maximum busses we need.

if this is still not clear think of it like this,
imagine a number line. the question has not specified how many busses the company owns, therefore this number line will go on forever.
(ex: 1, 2, 3, 4, 5, 6, 7, and so on)
saying that you need more than 11 busses is vague cuz there are infinite number of values above 11
but saying you need less than 11 busses means (since you cant have 0 busses) you start from 1 and you count toward to 11. it gives you a set value. that's why you take X less than or equal to N, to find the maximum value of N.

hope this helps. you've got to use some common sense in this question.

[shaheerahmed]

How did you know that x is greater than or equal to n in question 3B?

[anasbenchekroun]

Very useful video but ngl way too many ads my friend