A random sample of size 100 was selected from a pool of university students and they were asked whether they use Facebook on a regular basis. Fifty replied yes. What would be your 90% confidence interval estimate of the population proportion of regular Facebook users based upon the given information? (Hint: use 1.65 as the critical z-value)

	[35.7%, 64.3%]
	[37.8%, 62.3%]

	[39.8%, 60.3%]
	[41.8%, 58.3%]

Which of the following statements are correct regarding confidence intervals and sample size?

	Greater confidence requires narrower Confidence Interval.
	Smaller sample size gives narrower Confidence Interval.

	Larger sample size gives narrower Confidence Interval.
	Sample size has no impact on the size of Confidence Intervals.

It is known that the population standard deviation of the IQ test results is 16. Assuming that we have a random sample of 135, what is the standard error of the average IQ of a sample of this size?

1.38
	1.83

	2.71
	3.16

Two hundred undergraduate students were randomly selected from a university that has 47,000 students in total. Systolic blood pressure was tested on the 200 students. The sample standard deviation is 10.6 mmHg. What is the estimated standard error of the sample mean?

	0.05
	0.75

	1.50
	3.00