QUESTION 1

A population has an average of 150,000 with a standard deviation of 27,000.A random sample of 81 items is chosen.What is the standard error?

QUESTION 2

A population has a mean of 250, size of 1000, and a standard deviation of 7. A sample size of 50 was selected. Calculate the standard error. (3 decimal places)

QUESTION 3

A population has an average of 200 with a standard deviation of 25.A random sample of 64 items is chosen.What is the smallest interval that will contain 91.46% of the sample means?

Standard error (3 decimal places) =

Z =

Larger sample mean (1 decimal place) =

Smaller sample mean (1 decimal place)=

QUESTION 4

The average income in the city of Red Deer is $85,000 with a standard deviation of $20,000.A random sample of 100 residents is chosen.

What is the probability that a sample will be between $80,000 and $90,000?

Standard error =

Z = (Enter one of the Z-values)

Area =

Answer =

QUESTION 5

The average income in the city of Red Deer is $85,000 with a standard deviation of $20,000.A random sample of 100 residents is chosen.

What is the probability that a sample will be less than $87,500?

Z =

Area =

Answer =

QUESTION 6

In a population of 250 people, it is known that the population average is 1.56 with a standard deviation of 0.15.A random sample of 40 people are chosen.What is the smallest interval that will contain 95% of the sample means?

Standard error (3 decimal places) =

Z = (Enter one of the Z values)

Larger sample mean =

Smaller sample mean =

QUESTION 7

A population has an average of 125 and a standard deviation of 15. Calculate the probability that in a sample of size 75, the sample mean is greater than 130.

State the standard error. (state your answer to 2 decimal places)

State the Z-value

State the area

What is the final probability?

QUESTION 8

A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spend studying per week. Based on a simple random sample, they surveyed 144 students. The statistics showed that students studied an average of 20 hours per week. The population standard deviation is 10 hours. What is the standard error of the mean?

		10
		2
		12
		0.83

QUESTION 9

Suppose a research firm conducted a survey to determine the average amount of money steady smokers spend on cigarettes during a week. Sample size is 100. The population mean is $20 and the population standard deviation is $5. What is the probability that a sample of 100 steady smokers spend within $1 of the mean?

Determine the standard error

Calculate the Z-value (report only 1 of the Z-values)

Area

Answer

QUESTION 10

A population has an average of 125 and a standard deviation of 15. Calculate the probability that in a sample of size 75, the sample mean is less than 130.

State the standard error. (state your answer to 2 decimal places)

State the Z-value

State the area

What is the final probability?

QUESTION 11

In a large population, the average heating bill (which follows a normal distribution) is $145 with a standard deviation of 12. A sample of 60 residents is taken. What is the range for which 90% of samples will be within?

State the standard error. (state your answer to 3 decimal places)

State the Z-value (State one of the Z-values)

State the larger X value (1 decimal place)

State the smaller X value (1 decimal place)