LemuelBeemon
7

# A manufacturer of batteries knows that 10% of the batteries produced by a particular production line are defective. A sample of 200 batteries is removed for testing. a) What is the probability that exactly 20 batteries in the sample are defective? [2 marks] b) What is the probability that at least 20 batteries in the sample are defective? [7 marks]

I think you need only an answer without expanation so let's start. a) $P = \frac{200!}{180!x20!} * 0,1^{20}*0,9^{180} = 0.093636$ b) $Probability = 0.5 + \frac{1}{2} (0.093636) = 0.54682$