Question 5 - A-Level Maths

Exam Board	Edexcel
Module	S2 (Statistics 2)
Year	2009
Session	June
Topic	Approximating the Binomial to the Poisson distribution
Type	Calculate single probability using Poisson approximation

An administrator makes errors in her typing randomly at a rate of 3 errors every 1000 words.
1. In a document of 2000 words find the probability that the administrator makes 4 or more errors.
The administrator is given an 8000 word report to type and she is told that the report will only be accepted if there are 20 or fewer errors.
Use a suitable approximation to calculate the probability that the report is accepted.