# NCERT Mathematics Class 9 Exemplar Ch 14 Statistics and Probability Part 12

Q.18. Bulbs are packed in cartons each containing 40 bulbs. Seven hundred cartons were examined for defective bulbs and the results are given in the following table:

 Number of defective bulbs 0 1 2 3 4 5 6 more than 6 Frequency 400 180 48 41 18 8 3 2

One carton was selected at random. What is the probability that it has?

(i) No defective bulb?

(ii) Defective bulbs from 2 to 6?

(iii) Defective bulbs less than 4?

Q.19. Over the past 200 working days, the number of defective parts produced by a machine is given in the following table:

 Number of defective parts 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Days 50 32 22 18 12 12 10 10 10 8 6 6 2 2

Determine the probability that tomorrow’s output will have

(i) No defective part

(ii) At least one defective part

(iii) Not more than 5 defective parts

(iv) More than 13 defective parts

Q.20. A recent survey found that the ages of workers in a factory is distributed as follows:

 Age (in years) 20 - 29 30 - 39 40 - 49 50 - 59 60 and above Number of workers 38 27 86 46 3

If a person is selected at random, find the probability that the person is:

(i) 40 years or more

(ii) Under 40 years