Q16 of 24 Page 97

The survey has been undertaken to determine whether there is a relationship between the place of residence and ownership of an automobile. A random sample of car owners, 200 from large cities, 150 from suburbs and 150 from rural areas were selected and tabulated as follow


If a car owner was selected at random, what is the probability that he/she


(i) owns a foreign car.


(ii) owns a foreign car and lives in a suburb.


(iii) lives in a large city and does not own a foreign car.


(iv) lives in large city and owns a foreign car.


(v) neither lives in a rural area nor owns a foreign car.

(i) Total car owners = 500


Owners of foreign cars = 90 + 60 + 25 = 175




(ii) Total car owners = 500


Owners of foreign cars living in suburb = 60




(iii) Total car owners = 500


Owners of cars which is not foreign and live in large city = 110




(iv) Total car owners = 500


Owners of foreign cars living in large cities = 90




(v) Total car owners = 500


Owners not living in rural areas belongs to 4 different categories


(a) foreign car-Large City


(b) foreign car-Suburb


(c) non-foreign car-Large City


(d) non-foreign car-Suburb


Now, according to the question, among these four categories the owners should also not own a foreign car.


we now have 2 categories left


(c) non-foreign car-Large City


(d) non-foreign car-Suburb


No. of owners in category (c) = 110


No. of owners in category (d) = 90




More from this chapter

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14

The following table shows the results of a survey of thousand customers who bought a new or used cars of a certain model


If a customer is selected at random, what is the probability that the customer


(i) bought a new car (ii) was satisfied (iii) bought an used car but not satisfied

15

A randomly selected sample of 1,000 individuals were asked whether they were planning to buy a new cellphone in the next 12 months. A year later the same persons were interviewed again to find out whether they actually bought a new cellphone. The response of both interviews is given below


If a person was selected at random, what is the probability that he/she


(i) had a plan to buy (ii) had a plan to buy but a non-buyer


(iii) had no plan to buy but a buyer.

17

The educational qualifications of 100 teachers of a Government higher secondary school are tabulated below


If a teacher is selected at random what is the probability that the chosen teacher has


(i) master degree only (ii) M.Phil and age below 30 (iii) only a bachelor degree and age above 40(iv) only a master degree and in age 30-40 (v) M.Phil and age above 40

18

A random sample of 1,000 men was selected and each individual was asked to indicate his age and his favorite sport. The results were as follows.


If a respondent is selected at random, what is the probability that


(i) he prefers Volleyball (ii) he is between 20 - 29 years old


(iii) he is between 20 and 29 years old and prefers Basketball


(iv) he doesn’t prefer Hockey (v) he is at most 49 of age and prefers Football.