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Tamil Nadu Board of Secondary EducationHSC Commerce Class 12

The time taken to assemble a car in a certain plant is a random variable having a normal distribution of 20 hours and a standard deviation of 2 hours. What is the probability that a car can be

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Question

The time taken to assemble a car in a certain plant is a random variable having a normal distribution of 20 hours and a standard deviation of 2 hours. What is the probability that a car can be assembled at this plant in a period of time. Between 20 and 22 hours?

Sum
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Solution

Let x denotes the time taken to assemable cars mean µ = 20 hours and S.D σ = 2 hours

The standard normal variate

z = `(x - mu)/sigma`

= `(x - 20)/2`

P(Between 20 and 22 hours) = P(20 < x < 22)

When x = 20

z = `(20 - 20)/2 = 0/2` = 0

When x = 22 

z = `(22 - 20)/2 = 2/2` = 1

P(20 < x < 22) = P(0 < z < 1)

= 0.3413

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Chapter 7: Probability Distributions - Miscellaneous problems [Page 172]

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Samacheer Kalvi Business Mathematics and Statistics [English] Class 12 TN Board
Chapter 7 Probability Distributions
Miscellaneous problems | Q 6. (ii) | Page 172

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