Question

A lot consists of 144 ball pens of which 20 are defective and the others are good.Rafia will buy a pen if it is good but will not buy if it is defective. The shopkeeper draws one pen at random and gives it to her. The probability that she will buy that pen is

• A. $\frac{5}{36}$
• B. $\frac{20}{36}$
• C. $\frac{31}{36}$
• D. $\frac{31}{144}$

Answer 1

The Correct Option is C

Given: A lot of 144 ball pens, where 20 are defective and the remaining are good.

Step 1: Understanding the Probability of Selecting a Good Pen

Total pens = 144

Defective pens = 20

Good pens = 144 - 20 = 124 

Step 2: Probability Calculation

Probability of selecting a good pen = Number of good pens / Total number of pens

= 124 / 144 = 31 / 36

Final Answer: 31 / 36