# Example 26 - Chapter 13 Class 12 Probability

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Example 26 Let X denote the number of hours you study during a randomly selected school day. The probability that X can take the values x, has the following form, where k is some unknown constant. P(X = x) = 0.1 , =0 , =1 2 5 , =3 4 0, (a) Find the value of k Making in tabular format Since X is a random variable , its Sum of Probabilities is equal to 1 0 4 ( ) = 1 P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) = 1 0.1 + k + 2k + 2k + k = 1 6k = 1 0.1 6k = 0.9 k = 0. 9 6 k = 0.15 Example 26 (b) What is the probability that you study atleast two hours? Exactly two hours? At most 2 Hours Our probability distribution table is P(you study atleast two hours) = P(X 2) = P(X = 2) + P(X = 3) + P(X = 4) = 2k + 2k + k = 5k = 5 0.15 = 0.75 P(you study exactly two hours) = P(X = 2) = 2k = 2 0.15 = 0.30 P(you study atmost two hours) = P(X 2) = P(X = 0) + P(X = 1) + P(X = 2) = 0.1 + k + 2k = 0.1 + 3k = 0.1 + 3 0.15 = 0.1 + 0.45 = 0.55

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Chapter 13 Class 12 Probability

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About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.