Question

"Suppose we have a simple random sample comprised of the following data: 12, 46, 22, 21, 7. What is the point estimate of the population standard deviation?"

		15.01
		21
		21.6
		None of the above

Lots of things impact sampling error. Which one of the following does not?

		the variability of the population.
		the expected value of the sample statistic
		the sample size.
		the sampling method used.

"Given the information provided, what is the probability of obtaining a sample mean within +/- 2 of the population mean? Population information: mean = 425, and standard deviation = 25. Sample size is 210."

		0.9332.
		0.123.
		0.754.
		0.877.

A sample size of 95 is selected from a population with the proportion equal to 0.41. The sample proportion has an expected value of __ and standard deviation of __.

		0.41 and .0505
		0.41 and 0.41
		41 and 0.0505
		41 and 0.41

The CEO of Snapchat thinks that 65% of users are under the age of 25. A simple random sample of 70 users will be used to estimate the proportion of those under the age of 25. What is the probability the sample proportion will be between 0.6286 and 0.6714?

		0.648
		0.296
		0.352
		0.65

Answer 1

(1)

Correct option:

15.01

Explanation:
SD of the given data set = 15.01

(2)

Correct option:

the variability of the population

Explanation:

A sampling error is a statistical error that occurs when an analyst does not select a sample that represents the entire population of data. So, the variability of the population does not impact the sampling error.

(3) Correct option:

= 425

= 25

n = 210

SE = /

= 25/

= 1.7252

Z = ()/SE

= 2/1.7252=1.16

Table gives area = 0.3770

So,

Probability within 2 is given by: 2 X0.3770 = 0.7540

So,

Correct option:

0.754

(4)

Expected value of sample proportion = 0.41

SE =

So,

Correct option:

0.41 and 0.0505

(5)

To find P(0.6286 < < 0.6714):

Case 1: For from 0.6286 to mid value:

Z = (0.6286 - 0.65)/0.0570 = - 0.38

Table gives area = 0.1480

Case 2: For from mid value to 0.6714:

Z = (0.6714 - 0.65)/0.0570 = 0.38

So,

P(0.6286 < < 0.6714) =2 X 0.1480 = 0.2960

So,

Correct option:

0.296