1. Long distance phone calls have a normal distribution with x =5 minutes and x

Question

1. Long distance phone calls have a normal distribution with x =5 minutes and x =2 minutes.
Taking a unit on the rise.
a. What is the probability that a call is between 6 minutes and 10 minutes? b. What is the probability that a call takes more than 4 minutes? 1. Long distance phone calls have a normal distribution with x =5 minutes and x =2 minutes.
Taking a unit on the rise.
a. What is the probability that a call is between 6 minutes and 10 minutes? b. What is the probability that a call takes more than 4 minutes?
Taking a unit on the rise.
a. What is the probability that a call is between 6 minutes and 10 minutes? b. What is the probability that a call takes more than 4 minutes?
a. What is the probability that a call is between 6 minutes and 10 minutes? b. What is the probability that a call takes more than 4 minutes?

Explanation / Answer

mean = 5 , s = 2

a) P( 6 < x < 10)

z = ( x - mean) / s
= ( 6 -5 ) / 2
= 0.5

z = ( x - mean) / s
= ( 1 0- 5) / 2
= 2.5

P( 6 < x < 10) = P(0.5 < z < 2.5) = 0.3023

b)
P(X > 4)
z = ( x - mean) / s
= ( 4 -5 ) / 2
= -0.5
P(X >4) = P( z > -0.5) = 0.6915

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