### Recent Question/Assignment

Question 11
A stratified random sample is characterised by
(a) random selection of strata included
(b) all strata being represented in the sample in proportion to their representation in the population
(c) all members of selected strata being included in the sample
(d) the same number of members selected from each strata
(e) all the above
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Question 14
The auditor for a large bank in Australia knows that the monthly balance of any given customer is \$112 on average and the standard deviation is \$56. If the bank selects 49 accounts, what is the probability that the sample average monthly balance is between \$100 and \$130?
(a) 0.079
(b) 0.9878
(c) 0.921
(d) 0.9332
(e) Cannot be determined unless the monthly balance of any given customer account is normally distributed
Question 15
The auditor for a large bank in Australia knows that the monthly balance of any given customer account is \$112 on average and the standard deviation is \$56. If the bank selects nine (9) accounts, what is the probability that the sample average monthly balance is below \$100?
(a) 0.6428
(b) 0.7611
(c) 0.2611
(d) 0.7389
(e) Cannot be determined unless the monthly balance of any given customer account is normally distributed
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Question 19
In evaluating the effectiveness of the state rehabilitation program, a survey of 49 prisoners (several thousand prisoners in prison) found that 35 percent were repeat offenders. What is the 90 percent confidence interval for the proportion of repeat offenders among the prisoners?
(a) 0.22 & 0.48
(b) 0.52 & 0.78
(c) 0.54 & 0.76
(d) 0.22 & 0.46
(e) Cannot be calculated.
Question 20
A manufacturer of fishing rods makes their rods from a composite material that is baked for a given amount of time and at a given temperature. The standard deviation of the breaking strength of the rods is 2.25 kg. What size sample must be taken in order that the total width of the 95% confidence interval for the population mean will not be greater than 0.3 kg?
(a) 3458
(b) 865
(c) 441
(d) 217
(e) 30