Download Name: Date: Unit 5 (Part 1- Ch 18 and 19) Test Review Inferring

Name: _____________________________________________________________________ Date: ___________________
Unit 5 (Part 1- Ch 18 and 19) Test Review
Inferring statistics about your sample:
1) We can put all samples of a population onto a ______________________ ____________________ if
it meets the following three conditions:
a. ________________________________________________________________ (unbiased)
b. ________________________________________________________________ (large enough)
c. ________________________________________________________________ (small enough)
2) Based on the data, 25% of students taking the SAT score an 1800 or above.
a. Can a sample of 100 be approximated normally? Check conditions/assumptions.
b. Describe the sampling distribution for the population of all students taking the SAT.
c. If you have a sample of 100 students, what is the probability that more than 30% of
the sample scores over an 1800?
d. What is the probability that less than 20% of the sample scores an 1800 or more?
3) Based on the data, the average SAT score is a 1490 with a standard deviation of 300.
a. Can a sample of 50 be approximated normally? Check conditions/assumptions.
b. Describe the sampling distribution for the population of all students taking the SAT.
c. If you have a sample of 50 students, what is the probability that the average score is
above a 1500?
d. What is the probability that the average score is less than a 1400?
Inferring statistics about the population given info about the sample:
4) The formula for the confidence interval:
5) The formula for the margin of error (how off our sample data may be from the
population data):
6) A high school teacher wants to see how many students watch more than 1 hour of tv or
video games per night. She takes a random sample of 80 of her students. In her sample
she saw that 58 students watched/played more than 1 hour.
a. Check necessary conditions and state assumptions to be able to approximate using
a normal model.
b. Find a 99% confidence interval for the true proportion of the students who
watch/play over an hour/night. Write the sentence to interpret the interval.
7) The week before the primary election in Illinois you decide to conduct a study to see
who will win. If you want to construct a 95% confidence interval with a 7% margin of
error, how many people do you need to poll?
8) You are surveying 110 Noble graduates about whether or not Pritzker prepares you for
college. You find that 88 felt better prepared for college. You want to estimate this for
all Noble graduates within 8% of the true proportion. How confident can you be in the
interval? Write the sentence of interpretation.
Conceptualizing Chapter 18 and 19:
9) What is the difference between a population distribution, a sample distribution, and a
sampling distribution?
Population distribution:
Sample distribution:
Sampling distribution:
10)Label the following with the appropriate symbol:
N = _______population size_______________________________________
n = ________________________________________________________________
p = ________________________________________________________________
q = ________________________________________________________________
p = ________________________________________________________________
q = ________________________________________________________________
μ = ________________________________________________________________
σ = ________________________________________________________________
μx = _______sampling distribution mean________________________
σx = ______sampling distribution standard deviation_________
11)The two formulas for σx are:
a. When given a population proportion: ________________________________
b. When given a population mean and standard deviation: _____________________________
12)When we are calculating a confidence interval, we are giving a range of possible values
for the unknown
______________________________________ ___________________________________
13)If you lose confidence in that interval, your range for the possible population true
proportions gets ________________________________.
14)As your sample size gets bigger (as n gets bigger) what happens to your standard error
(the variability of the samples)?
So what happens to your confidence interval as your sample size gets bigger?