Question

Suppose the pen drawn in (i) is defective and is not replaced. Now one more pen is drawn at random from the rest. What is the probability that this pen is:

1. defective
2. not defective?

Answer 1

If defective pen drawn in first draw is not replaced, total possible outcomes = 20 – 1 = 19 

a. Number of defctive pens = 3 

P(defective pens) = `3/19` 

b. Number of not defective pens = 16 

P(not defective pens) = `16/19`