SOLUTION: The time required to finish a test in normally distributed with a mean of 80 minutes and a standard deviation of 15 minutes. What is the probability that a student chosen at rando

Algebra ->  Probability-and-statistics -> SOLUTION: The time required to finish a test in normally distributed with a mean of 80 minutes and a standard deviation of 15 minutes. What is the probability that a student chosen at rando      Log On


   

Question 618770: The time required to finish a test in normally distributed with a mean of 80 minutes and a standard
deviation of 15 minutes. What is the probability that a student chosen at random will finish the test in more
than 110 minutes?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

The time required to finish a test in normally distributed with a mean of 80 minutes and a SD = 15 minutes

110 would be 2 SD greater than the mean

P( x>110) = P(t> 2) = (1 - .954)/2 = .023



For the normal distribution: 

one  standard deviation from the mean accounts for about 68.2% of the set 

two standard deviations from the mean account for about 95.4% *****

and three standard deviations from the mean account for about 99.7%.