#### Question

4 defective pens are accidentally mixed with 16 good ones. It is not possible to just look at a pen and tell whether or not it is defective. One pen is drawn at random from the lot. What is the probability that the pen is defective?

#### Solution

Total number of pens = 4+16=20

Total possible outcomes=20

Number of defective pens=4

p(defective pen)=`4/20=1/5`

Is there an error in this question or solution?

Solution 4 Defective Pens Are Accidentally Mixed with 16 Good Ones. It is Not Possible to Just Look at a Pen and Tell Whether Or Not It is Defective. One Pen is Drawn at Random from the Lot. What is the Probability that the Pen is Defective? Concept: Probability - A Theoretical Approach.