SOLUTION: The number of cell phone minutes used by high school seniors follows a normal distribution with a mean of 500 and a standard deviation of 50. What is the probability that a student

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Question 471151: The number of cell phone minutes used by high school seniors follows a normal distribution with a mean of 500 and a standard deviation of 50. What is the probability that a student uses fewer than 600 minutes?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

Note: P(z ≥ 2) = .0228  (Table,calculators, etc) Excel: NORMSDIST(-2) = .0228

mean of 500 and a standard deviation of 50

P( x < 600min) 

 z = (600-500)/50 = 100/50 = 2   Note: P(z ≥ 2) = .0228

P( x < 600) = P(z < 2)=  1 - P(z ≥ 2) = 1 - .0228 = .9772