Download Suppose that a Normal model described student scores in a history

Z-Score and Normal Distribution Review
Tuesday, October 29th
Do Now: The mean score on our last quiz was an 83% with a standard deviation of 4 points.
Draw the normal model and clearly label using the 68-95-99.7 Rule.
a.)
If you scored 1.5 standard deviations above the mean, what was your score?
b.)
What percent of students earned below a 71% on the quiz?
c.)
What percent of students earned over 90% on the quiz?
History Test Suppose that a Normal model described student scores in a history class. Parker
has a standardized score (z-score) of +2.5. This means that Parker
A) is 2.5 points above average for the class.
B) is 2.5 standard deviations above average for the class.
C) has a standard deviation of 2.5.
D) has a score that is 2.5 times the average for the class.
E) None of the above.
Class Work
Veterinary costs Costs for standard veterinary services at a local animal hospital follow a
Normal model with a mean of $80 and a standard deviation of $20.
a. Draw and clearly label this model.
b.
What percent of veterinary bills are over $120?
c.
What percent of bills were between $50 and $115?
d.
Is it unusual to have a veterinary bill for $125? Explain, including the percent of bills
that are over $125.
Homework
Tuesday, October 29th
Birth Weights Birth weights of babies are normally distributed with a mean of 7.6 lbs. and a
standard deviation of 1.3 lbs.
a. Find the percent of babies that are born weighing more than 10.2 lbs.
b. In what weight range do 68% of babies fall?
c. How many standard deviations from the mean is a baby weighing 8.4 lbs.?
d. If a mother receives her baby’s weight as a z-score of 3, how much does her baby
weigh?
e. Which is more unusual: a baby weighing 4 pounds, or a baby weighing 11 pounds?
f. What percent of babies weigh more than 9.3 lbs.?