ALL ABOUT STATS - NO EXPLANATION NEEDED

1. Which of the following summarizes the sample by a single number that is an estimate of the population parameter? (a) point estimate (c) estimate (b) estimator (d) mean 2. What is the formula for confidence interval? (a) Point Estimate + Margin of Error (c) Point Estimate + Critical Value (b) Point Estimate + Standard Error (d) Point Estimate + Standard Deviation 3. What is a confidence level? (a) It is the range of values within which the true parameter lies. (b) It forms an interval within which the parameter is expected to lie. (c) It is a pair of numbers formed by the interval estimator. (d) It is the percentage of all possible samples that can be expected to include the true parameter. 4. When do we use the z-distribution? (a) When the sample size is less than 30. (b) When the sample size is less than 30 and the sample standard deviation is known. (c) When the population is normal and its standard deviation is known. (d) When the standard deviation is unknown. 5. What are the 3 most commonly used confidence levels? (a) 80%, 90%, 100% (c) 90%, 95%, 99% (b) 90%, 95%, 100% (d) 90%, 97%, 99.99%Eu What is the difference between the t-disb'ibub'on and the standard normal distribution? {at They are the same thing. [b] The standard normal distribution is symmetric while the t-distrbution is skewed. to] The standard normal distribution is bell-shaped while the t-distrbution is not. [d] They are both bell-shaped but the t-distributjon has greater area in the tails. T. 1llll'hen do we use the t-distribution'? ta) The population is normal. the pooulatjon standard deviation is unknown. and the sample size is less than 3D. {b} The population is normal. the population standard deviation is unknown. and the sample size is equal to SD. (c) The population is normal, the population standard deviation is unknown. and the sample size is greater than 3d. {d} We can use the t-distribution in any case. B. How do we compute the level of significance? {at Subtract the confidence level from 1. {hi Add the condence level to 1. [c] Subtract 1 from the confidence level. {d1 Divide the confidence level by 2 then subtract from 1. 9. How do we compute the length of a confidence interval? [a] Subtract the lower bound from the upper bound. [b] Double the margin of error. [c] Double the z-score times standard error. id] All of these are correct. 1D. Which of the following is true about sample size? [a] The sample size is the same as population size. [b] The sample size needs to be at least t. [c] The sample size is part of the population chosen for a survey. [d] The sample size cannot be less than 3D. 11. Which statement is not true about confidence intervals? {at A confidence interval is an interval of values computed from sample data that is likely to include the true population value. [b] An approximate formula fora 95% confidence interval is sample estimate :l: margin of error. [c] A condence interval between 213% and was means that the population proportion lies between 20% and cos. [d] A 99% confidence interval procedure has a higher probability of producing intervals that will include the population parameter than a 95% confidence interval procedure. 12. The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the {a} confidence level {bi margin of error [c] standard error {:1} interval estimate 13. in developing an interval estimate. it the population standard deviation is unknown {at it is impossible to develop an interval estimate {bl the standard deviation is arrived at using the range [c] the sample standard deviation can be used {d} it is assumed that the population standard deviation is 1 14. If the point estimate is El and the margin of error is 5 titan the confidence interval is {at {3.131 is} {5.15} {hi {4.141 id} (6.15} 15. A national random sample of 20 NCAE scores from 201i] is listed below. 29.25, 1123.23.25, 12,22.12.19.12.2s.3o.3o. is. 14.12.26.111, 13 Calculate the 95% confidence interval for the mean NCAE score based on the t-distribution. {at tm.23.o5) (c) nan-r. 23.53) [bl sac-.2115) is) {13.22.23.413} 16. Which one of the following random variables would require that the confidence interval for the proportion, rather than the mean, be used? (a) the number of employees who vote "in favor," rather than "against," a new over-time policy (b) the weight in pounds of bags of fertilizer (c) the volume in ounces of bottle fill-weight (d) the number of sales per employee in 2008 17. The z-value which is used to construct a 99% confidence interval is: (a) 2.58 (c) 1.65 (b) 1.96 (d) 1.28 18. A 95% confidence interval for the mean can be interpreted to mean that: (a) if all possible samples are taken and confidence intervals are calculated, 95% of those intervals would include the true sample mean somewhere in their interval. (b) if all possible populations are taken and confidence intervals are cal- culated, 95% of those intervals would include the true sample mean somewhere in their interval. (c) you can be 95% confident that you have selected a sample whose interval does not include the population mean. (d) if all possible samples are taken and confidence intervals are calcu- lated, 95% of those intervals would include the true population mean somewhere in their interval. 19. You and your friend decide to construct 95% confidence intervals for a given population mean. You wind up taking a sample of 49 random observations while your friend's sample is made up of 36 random observations. Which of the following is true? (a) Your friend's interval has a greater degree of confidence. (b) Your interval has a greater degree of confidence. (c) The total width of your confidence interval estimate is narrower. (d) The total width of your confidence interval estimate is wider. 20. The width of a confidence interval for a proportion will be: (a) narrower for 99% confidence than for 95 (b) wider for 90% confidence than for 95 (c) wider when the sample proportion is 0.50 than when the sample propor- tion is 0.20. (d) wider for a sample of size 100 than for a sample of size 50.21. 22. 24. 25. When determining the sample size for a mean for a given level of confidence and standard deviation. if the margin of enor is allowed to increase. the sample size required [a] cannot bedstermined. to} willdecrease. [b] will increase. (d) will strut)r the same. "the value of 2 selected for constructing a given confidence interval is called the {a} critical value to} error {bl student (d) confidence . When estimating the population mean with a small sample. the t-distribution may,r be used with _ degrees of freedom. is] n {c} n+1 {bl "1 {d} l A sample of 50 students was taken from the local university. These students spent an average of $1?!) on books this semester. with a standard deviation of $255!]. A 95% confidence interval for the average spent on books for all students would he {a} 1?[l:l:5.95 [c] [Mil-162 {s1 mass: to} None of these The t-value that would be used to construct a 99% confidence interval for the mean wilh a sample of size n = 1? would he {a} 2.921 [c] 2.533 to] 2.393 {a} 2.56