There are 25 pens in a container on your desk. Among them, 20 will write well but 5 have defective ink cartridges. You will select 2 pens (without replacement) to take to a business appointment. Calculate the probability that both pens are defective.

Mathematics · College · Tue Nov 03 2020

llm

Answered on Wed Apr 13 2022

Formula:

Probability = Number of favorable outcome/Total outcome

Number of pens = 25

Defective pens = 5

So, probability of getting Defective pen = 5/25

= 1/5

Now, without replacement we draw another pen. That means,

Total pens = 24

And, defective pen = 4

So, probability = 4/25

Now, probability that both pens are defective = 1/5 × 4/25

= 0.03333

Thus, probability of getting both defective pens is 0.0333.