Lesson Example Discussion Quiz: Class Homework |
Example |
Title: Uniform distribution |
Grade: 9-a Lesson: S4-L8 |
Explanation: The best way to understand statistics is by looking at some examples. Take turns and read each example for easy understanding. |
Examples:
If X ~ U (200, 250) find its p.d.f and P (X > 230),mean, median and standard deviation.
Step 1a
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Finding the Probability density function |
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Explanation: For X∼ U(a,b) f(x) = \$1/(b-a)\$ a<x<b Given X∼ U(200,250) f(x) = \$1/(250-200)\$ 200<x<250 f(x) = \$1/50\$ 200<x<250 |
Step 1b
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Finding P (X > 230) |
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Explanation: P (X > 230) = \$\int_230^\infty f(x) dx\$ P (X > 230) = \$\int_230^250 1/50 dx\$ where f(x) = \$1/50\$ P (X > 230) = \$1/50\$ \$ (x)_230^250\$ P (X > 230) = \$(250-230)/50 = 20/50\$ P (X > 230) = 0.4 |
Step 1c
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Calculate the Mean,median,standard deviation. |
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Explanation: Given X∼ U(200,250) a = 200,b = 250 mean = median = \$(a+b)/2\$ mean = median = \$(200+250)/2\$ mean = median = \$450/2\$ mean = median = 225 Standard deviation = \$\sqrt((b-a)^2/12)\$ S.D = \$\sqrt((250-200)^2/12)\$ S.D = \$\sqrt(50^2/12)\$ S.D = \$\sqrt(2500/12)\$ S.D = \$50/\sqrt12\$ S.D = \$50/3.464\$ S.D = 14.434 |
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