The local council claims that the average number of accidents per year on a particular road is $$$0.8$$$. Jane claims that the true average is greater than $$$0.8$$$. She looks at the records for a random sample of 3 recent years and finds that the total number of accidents during those 3 years was 5. Jane finds that the number of accidents per year has been gradually increasing over recent years. State how this might affect the validity of the test carried out in part (a)(ii). ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................

Mathematics

IGCSE&ALevel

CAIE

Exam No：9709_s21_qp_63 Year：2021 Question No：3(b)

Answer:

Mean not constant so Poisson model not valid

6.1.3 understand the relevance of the Poisson distribution to the distribution of random events, and use the Poisson distribution as a model