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Identify the random variable as either discrete or continuous in each of the following. If the random variable is discrete, list its possible values: (i) An economist is interested in the number of unemployed graduates in the town of population 1 lakh. (ii) Amount of syrup prescribed by a physician. (iii) The person on a high protein diet is interesting to gain weight in a week. (iv) 20 white rats are available for an experiment. Twelve rats are males. A scientist randomly selects 5 rats, the number of female rats selected on a specific day. (v) A highway-safety group is interested in studying the speed (in km/hr) of a car at a checkpoint. |
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Answer» (i) Let X = number of unemployed graduates in a town. Since the population of the town is 1 lakh, X takes the finite values. ∴ random variable X is discrete. Range = {0, 1, 2, …, 99999, 100000}. (ii) Let X = amount of syrup prescribed by a physician. Then X takes uncountable infinite values. ∴ random variable X is continuous. (iii) Let X = gain of weight in a week Then X takes uncountable infinite values ∴ random variable X is continuous. (iv) Let X = number of female rats selected on a specific day. Since the total number of rats is 20 which includes 12 males and 8 females, X takes the finite values. ∴ random variable X is discrete. Range = {0, 1, 2, 3, 4, 5} (v) Let X = speed of .the car in km/hr. Then X takes uncountable infinite values ∴ random variable X is continuous. |
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