Mr. Rogers - AP Statistics Objectives

Unit Plan Practice Test Study Guide

			AP Statistics  Practice Test Sampling Distributions Confidence Intervals Chapt 9 & 10
	1	)	According to the central limit theorem, the sampling distribution: 1) gets narrower or has less variability and 2) more closely resembles a normal distribution as sample size increases..
	2	)	The average height all monkeys is 48 with a standard deviation of 2 inches. What is the standard deviation of monkey heights for the sampling distribution of size ten? SE = 2 / (10)0.5
	3	)	What effect does population size have on the mean and standard deviation of a sampling distribution? no effect on the mean or std dev
	4	)	Generally a statistic is used for estimating a corresponding parameter.
	5	)	Indicate which of the following can fit the binomial setting. Y=yes, N=no
			yes       If 90 % of consumers buy corn flakes then what is the probability of randomly choosing 100 who don't buy corn flakes. no , p is not constant  If a barrel of 10 monkeys contains 2 albino monkeys what is the probability of getting both albinos in a given draw assuming no monkeys are replaced after being drawn.
			no, p is not constant   If 45% of all students wore Bob's Jumpy Shoes in 1978 what is the probability of finding a random sample of 20 students that wear Bob's Jumpy Shoes the year 2057?
	6	)	If the width of a confidence interval triples, what also had to happen to the margin of error? 3x
	7	)	If the sample size is increased by a factor of 2, what is the effect on the margin of error? new ME change = (1 / (2)0.5)*(old ME)                           =  0.707(old ME)
	8	)	If the confidence level is changed from 80% to 95% what is the effect on the margin of error? % change = [(1.96-1.28) / 1.28]*100%                 = 53%
	9	)	Which type(s) of error(s) will the margin of error account for? Random sampling error or variability
	10	)	What is the z* for a confidence level of 85%? 1.44
	11	)	Which types of studies can make use of confidence intervals? SRS
	12		What is the minimum sample size for determining the mean length of widgets in a manufacturing industry to a margin of error = plus or minus .2 given a 90% confidence interval and a standard deviation = 3. ME = Z* ( σp/ n0.05) n  (ME) = Z* ( σp) n0.05 = (Z* σp) / (ME) n = [(Z* σp) / (ME)]2 n = [1.64(3) / (0.2)]2 n = 605.1  rounding up, use 606
	13	)	Which is more accurate, a margin of error with a confidence level of  65% or a margin of error with a confidence interval  of 90%? Can't tell.
	14	)	For an 80 % confidence interval, we are confident that _______________ .
			80 % of confidence intervals constructed around a sample statistic will contain the population parameter.