(i) She will buy it ?

(ii) She will not buy it ?

NCERT Class 10 Math’s Chapter 15 Probability

Page No. 310

Exercise 15.1

Question No. 21

# 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

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Total number of pens = 144

Total number of defective pens = 20

Total number of good pens = 144 – 20 = 124

(i) Probability of getting a good pen = 124/144 = 31/36

P (Nuri buys a pen) = 31/36

(ii) P (Nuri will not buy a pen) = 1 – 31/36 = (36 – 31)/36 = 5/36