     1. Chapter 15 Class 9 Probability (Term 2)
2. Serial order wise
3. Ex 15.1

Transcript

Ex 15.1, 5 An organization selected 2400 families at random and surveyed them to determine a relationship between income level and the number of vehicles in a family. The information gathered is listed in the table below: Suppose a family is chosen, find the probability that family chosen is (i) earning Rs 10000 − 13000 per month and owning exactly 2 vehicles. Number of total families surveyed = 2400 Number of families earning Rs 10000 ­− 13000 per month and owning exactly 2 vehicles = 29 Hence, required probability, P = 29/2400 Ex 15.1, 5 (ii) earning Rs 16000 or more per month and owning exactly 1 vehicle Number of total families surveyed = 2400 Number of families earning Rs 16000 or more per month and owning exactly 1 vehicle = 579 Hence, required probability, P = 579/2400 Ex 15.1, 5 (iii) earning less than Rs 7000 per month & does not own any vehicle Number of total families surveyed = 2400 Number of families earning less than Rs 7000 per month & does not own any vehicle = 10 Hence, required probability = P = 10/2400 = 1/240 Ex 15.1, 5 (iv) earning Rs 13000 – Rs16000 per month & owning more than 2 vehicles Number of total families surveyed = 2400 Number of families earning Rs 13000 – Rs16000 per month & owning more than 2 vehicles = 25 Hence, required probability = P = 25/2400 = 1/96 Ex 15.1, 5 (v) owning not more than 1 vehicle Number of total families surveyed = 2400 Number of families owning not more than 1 vehicle = Number of families owning 0 vehicles + Number of families owning 1 vehicle = (10 + 0 + 1 + 2 + 1) + (160 + 305 + 535 + 469 + 579) = 2062 Hence, required probability = P = 2062/2400 = 1031/1200

Ex 15.1 