NCERT Mathematics Class 9 Exemplar Ch 14 Statistics and Probability Part 12 (For CBSE, ICSE, IAS, NET, NRA 2022)

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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