Adf-Realtes
ST 509 Sample Questions - Test 2
Topics Distribution of the sample mean. Central Limit Theorem. Confidence intervals for a population mean. Confidence intervals for a population proportion. Sample size for a given confidence level and margin of error (proportions). Poll articles. Hypotheses tests for a mean, and differences in means (independent and paired samples). Sample size and power of a test. Type I and Type II errors. You will be given a table of normal probabilities. You may wish to be familiar with the follow formulae and their application.
x ± t! 2, n"1 s
n ;
( x1 " x2 ) ± t! 2, #
2 s12 s2 + n1 n2
;
p ± z! 2
p (1" p ) n
$ z! 2 ' ; n=& p (1" p ) % m ) (
2
1. _____ A confidence interval for the mean of a normal population turns out to be (4.20, 7.00). The margin of error then must be (A) 5.60 (B) 2.80 (C) 11.20 (D) 1.40
2. _____ The number of days between receipt of an order and shipment of goods for in-stock items is normally distributed with a mean of 3.0 days and a standard deviation of 0.5 days. For a randomly selected order, the probability that the receipt-to-order delay time is more than 4 days is (A) 0.1269 (B) 0.0228 (C) 0.0583 (D) 0.1557
3. _____ For the same situation as in Question #2 above, the probability that 6 randomly selected orders will have a sample mean receipt-to-order delay time of more than 3.2 days is 4. _____ A sample of n=25 observations is to be drawn from a population that is normally distributed with a mean of 4.0 and a standard deviation of 2.0. The probability that the sample mean of these observations will exceed 4.8 is (A) 0.3446 (B) 0.1287 (C) 0.2716 (D) 0.0228 (A) 0.1156 (B) 0.0718 (C) 0.3239 (D) 0.1635
5. _____ Student scores on a standardized test are normally distributed with a mean of 500 and a standard deviation of 110. Four student scores are selected at random. The probability that the average of these scores is between 445 and 610 is
(A) 0.8186
Topics Distribution of the sample mean. Central Limit Theorem. Confidence intervals for a population mean. Confidence intervals for a population proportion. Sample size for a given confidence level and margin of error (proportions). Poll articles. Hypotheses tests for a mean, and differences in means (independent and paired samples). Sample size and power of a test. Type I and Type II errors. You will be given a table of normal probabilities. You may wish to be familiar with the follow formulae and their application.
x ± t! 2, n"1 s
n ;
( x1 " x2 ) ± t! 2, #
2 s12 s2 + n1 n2
;
p ± z! 2
p (1" p ) n
$ z! 2 ' ; n=& p (1" p ) % m ) (
2
1. _____ A confidence interval for the mean of a normal population turns out to be (4.20, 7.00). The margin of error then must be (A) 5.60 (B) 2.80 (C) 11.20 (D) 1.40
2. _____ The number of days between receipt of an order and shipment of goods for in-stock items is normally distributed with a mean of 3.0 days and a standard deviation of 0.5 days. For a randomly selected order, the probability that the receipt-to-order delay time is more than 4 days is (A) 0.1269 (B) 0.0228 (C) 0.0583 (D) 0.1557
3. _____ For the same situation as in Question #2 above, the probability that 6 randomly selected orders will have a sample mean receipt-to-order delay time of more than 3.2 days is 4. _____ A sample of n=25 observations is to be drawn from a population that is normally distributed with a mean of 4.0 and a standard deviation of 2.0. The probability that the sample mean of these observations will exceed 4.8 is (A) 0.3446 (B) 0.1287 (C) 0.2716 (D) 0.0228 (A) 0.1156 (B) 0.0718 (C) 0.3239 (D) 0.1635
5. _____ Student scores on a standardized test are normally distributed with a mean of 500 and a standard deviation of 110. Four student scores are selected at random. The probability that the average of these scores is between 445 and 610 is
(A) 0.8186