Statistics Help - January 2019 Problem of the Month - Normal Distribution, Z-score

CAMBRIDGE, Mass. - Jan. 14, 2019 - PRLog -- The following exemplifies a general normal distribution problem normalized into a Z-score problem with usage of the Z-score table. Over 30% of the problems that Tutorteddy encounters are related to calculating Z-value.

Question:

Monthly Utility bills are normally distributed with a mean value of $160 and standard deviation of $25.
a. Find probability of bill between $120 and $180
b.Find probability of bill less than $120
c.Find probability of bill more than $210

Answer:

Define X as the monthly utility bill and Z as a standard normal random variable.
(a) P(120 < X < 180) = P((120-160)/25 < Z < (180-160)/25) = 0.7333
(b) P(X < 120) = P(Z < (120-160)/25) = 0.0548
(c) P(X > 210) = P(Z > (210-160)/25) = 0.0228

To see more examples or receive help, visit https://tutorteddy.com/site/free_statistics_help.php. You can also get help with accounting problems at https://tutorteddy.com/free_accounting_homework_help.php.

Free help is available if needed for 15 minutes or less.
Tutorteddy.com is committed to spreading knowledge and encouraging learning, but we cannot help students unless they want to learn. Learn how to learn from TutorTeddy, and enjoy the challenge of life long growth.