NCERT Exercise 14.1 - Q21(i) - Probability
Question: A lot consists of 144 ball pens of which 20 are defective and the others are good. Nuri 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. What is the probability that (i) she will buy the pen?
Answer: P = 31/36.
Full step-by-step NCERT solution with diagrams on Something by Zero.