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Statistics 101 Quiz - Statistics and Probability

Find the mean of the difference in sample proportions: E(p1 - p2) P1 - P2 0.52 - 0.47 0.05. Find the standard deviation of the difference. D sqrt P1(1 - P1) / n1, p2(1 - P2) / n2 d sqrt (0.52 0.48) / 100 (0.47 0.53) / 100 d sqrt (0.002496 0.002491) sqrt(0.004987) 0.0706 Find the probability. D  Large numbers eliminate sampling error. 2 A z-score of 2.0 is two standard deviations above the mean of the distribution (t). True, false 3 In a distribution for which the mean is 25 and the standard deviation is 5, what percentage of all scores occur between 20 and 30?

Because n1P1 100 0.52 52, n1(1 - P1) 100 0.48 48, n2P2 100 0.47 47, and n2(1 - P2) 100 0.53 53 are each greater than 10, the sample size is large enough. In a second state, 47 of the voters are Republicans, and 53 are. Democrats. Suppose a simple random sample of 100 voters are surveyed from each state. What is the probability that the survey will show a greater percentage of Republican voters in the second state than in the first state? A  2.262 b  2.228 c .05 d .01 6 In the z transformation formula, z (x M s the x stands for _. A  an unknown value b  the mean of the z distribution c  the standard deviation of the distribution d  the value to be transformed into z 7 Rejecting the null hypothesis is the same as saying _. C The z-test provides a way to evaluate how individuals compare to a population. D The z-test is based on how individual scores compare to a sample mean 5 What is the critical value of t for a two-tailed t-test in which n 10? The number of voters sampled from the first state (n1) 100, and the number of voters sampled from the second state (n2) 100. The solution involves four steps. Make sure the sample size is big enough to model differences with a normal population. True, false 9 The z scores is a ratio of difference to variability (t) True, false 10 Question 10 of 10 A z-score of