Question

A confidence interval, at the 95% confidence level, will be used to answer the question, "What is the mean annual salary (in US dollars) of a Tesla car owner?"  Data was collected from 36 Tesla owners across the US. The mean annual salary of those 36 Tesla owners was $254000.  The standard deviation of ALL Tesla owners is known to be $1057.

a)  The value at the center of the confidence interval represents what quantity?  Choose an option from the list and type its corresponding letter in the box.  

1. sample size
2. population mean
3. sample mean
4. standard deviation

Answer for (a):

b)  Is z* or t* used when building this confidence interval?  Choose an option from the list and type its corresponding letter (A or B) in the box.

1. z*
2. t*

Answer for (b):

A confidence interval, at the 95% confidence level, will be used to answer the question, "What is the mean annual salary (in US dollars) of a Tesla car owner?"  Data was collected from 36 Tesla owners across the US. The mean annual salary of those 36 Tesla owners was $254000.  The standard deviation of ALL Tesla owners is known to be $1057.

a)  The value at the center of the confidence interval represents what quantity?  Choose an option from the list and type its corresponding letter in the box.  

1. sample size
2. population mean
3. sample mean
4. standard deviation

Answer for (a):  

b)  Is z* or t* used when building this confidence interval?  Choose an option from the list and type its corresponding letter (A or B) in the box.

1. z*
2. t*

Answer for (b):  

c) Determine the value of the letter indicated in part (b) using one of the following tables:  normal table, t table. Type the number, recorded to 3 decimals, in the box.

Answers for (c):

d) What are the lower and upper bounds of this confidence interval?   Type the numbers, rounded to 2 decimals, in their corresponding boxes.

Answers for (d): Lower Bound - ? Upper Bound - ?

e) If the sample size is decreased to 20 Tesla owners, what would happen to the confidence interval?   Choose an option and write its corresponding letter the blank below.

1. It narrows.
2. It widens.
3. It does not change.

Answer for (e): ?

Answer 1