Question

Determine whether the

z

-test or the

t

-test should be performed, or whether a statistician should be consulted.

Part 1 of 3

A simple random sample of size

23

has mean

x

=

41.8

. The population standard deviation is σ

=

3.72

. The population is normally distributed. Can you conclude that the population mean differs from

40

?

The population standard deviation ▼(Choose one) known. The sample size n ▼(Choose one) greater than 30 . The population ▼(Choose one) approximately normal. The correct decision is to ▼(Choose one).

Part 2 of 3

A simple random sample of size

15

has mean

x

=

7.26

. The population standard deviation is σ

=

3.72

. The population is not approximately normal. Can you conclude that the population mean is greater than

9

?

The population standard deviation ▼(Choose one) known. The sample size n ▼(Choose one) greater than 30 . The population ▼(Choose one) approximately normal. The correct decision is to ▼(Choose one).

Part 3 of 3

A simple random sample of size

15

has mean

x

=

14.3

and the standard deviation is

s

=

1.9

. The population is not approximately normal. Can you conclude that the population mean differs from

10

?

The population standard deviation ▼(Choose one) known. The sample size n ▼(Choose one) greater than 30 . The population ▼(Choose one) approximately normal. The correct decision is to ▼(Choose one).

Answer 1

Part 1

The population standard deviation is known. The sample size n is not greater than 30. The population is approximately normal. The correct decision is to use a z test.

Part 2

The population standard deviation is known. The sample size n is not greater than 30. The population is not approximately normal. The correct decision is to use a z test.

Part 3

The population standard deviation is not known. The sample size n is not greater than 30. The population is not approximately normal. The correct decision is to consult an statistician.