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# problem library

1. ### A random sample of 40 adults with no children under the age of 18 years results in a mean daily leis

A random sample of 40 adults with no children under the age of 18 years results in a mean daily leisure time of 5.22 hours, with a standard deviation of 2.31 hours. A random sample of 40 adults with children under the age of 18 results in a mean daily leisure time of 4.29 hours, with a...
2. ### Six Years ago, 12.2% of registered births were to teenage mothers. A sociologist believes that the

Six Years ago, 12.2% of registered births were to teenage mothers. A sociologist believes that the percentage has decreased since then. (a) Which of the following is the hypothesis to be conducted? A. H0: p = 0.122, H1 p > 0.122 B. H0: p = 0.122, H1 p <> 0.122 C. H0: p = 0.122, H1 p <...
3. ### Construct a confidence interval of the population proportion at the given level of confidence. x = 1

Construct a confidence interval of the population proportion at the given level of confidence. x = 120, n = 300, 99% confidence Round to 3 decimal places as needed 0.327 < p < 0.473 using our proportion confidence interval calculator
4. ### Determine ux and sigma(x) from the given parameters of the population and sample size u = 76, sigma

Determine ux and sigma(x) from the given parameters of the population and sample size u = 76, sigma = 28, n = 49 ux = ? sigma(x) = ? u = ux = 76 sigma(x) = sigma/sqrt(n) so we have 28/sqrt(49) = 28/7 = 4
5. ### Determine the area under the standard normal curve that lies between:

Determine the area under the standard normal curve that lies between: (a) Z = -0.38 and Z = 0.38 (b) Z = -2.66 and Z = 0 (c) Z = -1.04 and Z - 1.67 (a) 0.2961 using our z score calculator (b) 0.4961 using our z score calculator (c) 0.8034 using our z score calculator
6. ### A binomial probability experient is conducted with the given parameters. Compute the probability of

A binomial probability experient is conducted with the given parameters. Compute the probability of x successes in the n independent trials of the experiment. n = 40, p = 0.05, x = 2 P(2) = Answer is 0.2777. Using Excel formula of =BINOMDIST(2,40,0.05,FALSE) or using our binomial probability...
7. ### Determine whether the random variable is discrete or continuous. In each case, state the possible v

Determine whether the random variable is discrete or continuous. In each case, state the possible values of the random variable. (a) The number of customers arriving at a bank between noon and 1:00 P.M. (i) The random variable is continuous. The possible values are x >= 0. (ii) The random...
8. ### Can a coefficient of determination be negative? Why or why not?

Can a coefficient of determination be negative? Why or why not? Yes, reasons below predictions that are being compared to the corresponding outcomes have not been derived from a model-fitting procedure using those data where linear regression is conducted without including an intercept...
9. ### Which of the following can increase power?

Which of the following can increase power? a. Increasing standard deviation b. Decreasing standard deviation c. Increasing both means but keeping the difference between the means constant d. Increasing both means but making the difference between the means smaller b. Decreasing standard...
10. ### As the sample size increases, we assume:

As the sample size increases, we assume: a. α increases b. β increases c. The probability of rejecting a hypothesis increases d. Power increases d. Power increases Power increases if the standard deviation is smaller. If the difference between the means is bigger, the power is bigger...
11. ### If the probability that you will correctly reject a false null hypothesis is 0.80 at 0.05 significan

If the probability that you will correctly reject a false null hypothesis is 0.80 at 0.05 significance level. Therefore, α is__ and β is__. α represents the significance level of 0.05 We want the Power of a Test which is 1 - β = 0.8 so β = 0.20 Our answer is: 0.05, 0.20
12. ### If power is big, you can assume:

If power is big, you can assume: a. The difference between the means is more likely to be detected b. The significance level set by the researcher must be high c. We increase the probability of type I error d. Your study result will be more likely to be inconclusive b. The significance level...
13. ### The probability of failing to reject a false null hypothesis is ____

The probability of failing to reject a false null hypothesis is ____ a. α b. 1 - α c. 1 - β d. β d. β
14. ### Which of the followings is the definition of power? a. Power is the probability of rejecting a null

Which of the followings is the definition of power? a. Power is the probability of rejecting a null hypothesis b. Power is the probability of accepting a null hypothesis c. Power is the probability of accepting a false null hypothesis d. Power is the probability of rejecting a false null...
15. ### Imagine a researcher wanted to test the effect of the new drug on reducing blood pressure. In this s

Imagine a researcher wanted to test the effect of the new drug on reducing blood pressure. In this study, there were 50 participants. The researcher measured the participants' blood pressure before and after the drug intake. If we want to compare the mean blood pressure from the two time periods...
16. ### Which of the followings can increase the value of t? (select all the apply) a. Increase the standar

Which of the followings can increase the value of t? (select all the apply) a. Increase the standard deviation of difference scores b. Decrease the standard deviation of difference scores c. Increase the difference between means d. Decrease the difference between means b. Decrease the standard...
17. ### A professor wants to test all possible pairwise comparisons among three means. If we need to maintai

A professor wants to test all possible pairwise comparisons among three means. If we need to maintain an experiment-wise alpha of 0.05, what is the error rate per comparison after applying Bonferroni correction? We are given: α = 0.05 n = 3 Bonferroni Correction = α/n Bonferroni Correction =...
18. ### A professor wanted to test all possible pairwise comparisons among six means. How many comparisons d

A professor wanted to test all possible pairwise comparisons among six means. How many comparisons did he need to compare? a. 5 b. 6 c. 10 d. 15 d. 15 using our combinations calculator
19. ### Which of the following involves making pairwise comparisons? a. Comparing the standard deviation of

Which of the following involves making pairwise comparisons? a. Comparing the standard deviation of GRE grades between two states b. Comparing the variance of the amount of soda consumed by boys and girls in a high school c. Comparing the mean weight between children in grades 2, 3, 4 and 5...
20. ### A researcher posed a null hypothesis that there was no significant difference between boys and girls

A researcher posed a null hypothesis that there was no significant difference between boys and girls on a standard memory test. He randomly sampled 100 girls and 100 boys in a community and gave them the standard memory test. The mean score for girls was 70 and the standard deviation of mean was...