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Tamil Nadu Board of Secondary EducationHSC Science Class 12

The cumulative distribution function of a discrete random variable is given byF(x) = {0 -∞<x<-10.15-1≤x<00.350≤x<10.601≤x<20.852≤x<313≤x<∞Find P(X ≥ 2)

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Question

The cumulative distribution function of a discrete random variable is given by
F(x) = `{{:(0,  - oo < x < - 1),(0.15, - 1 ≤ x < 0),(0.35, 0 ≤ x < 1),(0.60, 1 ≤ x < 2),(0.85, 2 ≤ x < 3),(1, 3 ≤ x < oo):}`
Find P(X ≥ 2)

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Solution

Given F(x) = `{{:(0,  - oo < x < - 1),(0.15, - 1 ≤ x < 0),(0.35, 0 ≤ x < 1),(0.60, 1 ≤ x < 2),(0.85, 2 ≤ x < 3),(1, 3 ≤ x < oo):}`

The value of 'x' are –1, 0, 1, 2, 3

F(–1) = P(X = –1)

= F(–1) – F(–1)

= 0.15 – 0

= 0.15

F(0) = P(X = 0)

= F(0) – F(–1)

= 0.35 – 0.15

= 0.20

F(1) = P(X = 1)

= F(1) – F(0)

= 0.60 – 0.35 =

0.25

F(2) = P(X = 2)

= F(2) – F(1)

= 0.85 – 0.60

= 0.25

F(3) = P(X = 3)

= F(3) – F(2)

= 1 – 0.85

= 0.15

P(X ≥ 2) = P(X = 2) + P(X = 3)

= 0.25 + 0.15

= 0.40

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Chapter 11: Probability Distributions - Exercise 11.2 [Page 194]

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Samacheer Kalvi Mathematics - Volume 1 and 2 [English] Class 12 TN Board
Chapter 11 Probability Distributions
Exercise 11.2 | Q 5. (iii) | Page 194

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