Unit 3: Chapter 8.3 Proportions

Question 1

Round to two decimal places. For a confidence level of 95%, find the positive critical z value

Answer 1

1.96

Question 1

Round to three decimal places. For a confidence level of 99%, find the positive critical z value

Answer 1

2.575

Question 2

A student was asked to find a 90% confidence interval for the proportion of students who take notes using data from a random sample of size n = 87. Which of the following is a correct interpretation of the interval 0.14 < p < 0.24?

Answer 2

With 90% confidence, the proportion of all students who take notes is between 0.14 and 0.24.

Question 3

Beyond representative sampling, what assumptions are needed to satisfy the requirements of a one-sample proportion interval?

Answer 3

The number of successes and failures should both be at least 5 and the number of successes should follow a binomial distribution

Question 4

For a confidence level of 87%, find the positive critical value for a confidence interval on a one sample proportion.

Answer 4

significance level= 1-confidence level
=1-.87=0.13
0.13/2=0.065
look this up on z table
=1.51

Question 5

Determine whether the following statement is true or false:

Answer 5

False

Question 6

The mean of a normal distribution is

Answer 6

μ

Question 7

The mean of a standard normal distribution is

Answer 7

0

Question 8

The standard deviation of a standard normal distribution is

Answer 8

1

Question 9

The standard deviation of a normal distribution is

Answer 9

σ

Question 10

The variance of a normal distribution is

Answer 10

σ squared

Question 11

Another name for a normal distribution is the z distribution

Answer 11

False, its the z distribution is also standard normal distribution

Question 12

Suppose you compute a confidence interval with a sample size of 28. What will happen to the confidence interval if the sample size increases to 67?

Answer 12

Narrow, bigger sample means narrow interval

Question 13

Suppose you compute a 99% confidence interval. What will happen to the confidence interval if you decrease the confidence level to 97%?

Answer 13

The confidence interval will narrow, decreasing confidence level means narrow interval