1.
t0.01=2.602
-t0.05=-1.729
+-t0.025=+-2.179
2.
t=1.321
-t=2.426
+-t=+-2.449
3.
t0=-1.379
-t0.05=-1.714
Skip this problem.
There is not enough evidence for the researcher to reject the null hypothesis because it is a left-tailed test and the test statistic is greater than the critical value -1.379>-1.714
4.
t0=2.502
t=2.819
Skip this problem.
There is enough evidence for the researcher to reject the null hypothesis because it is a right-tailed test and the test statistic is greater than the critical value 2.674>1.318
5.
t0=2.502
-t0.05=2.819, t0.05=2.819
Skip this problem.
There is not sufficient evidence for the researcher to reject the null hypothesis, since the test statistic is between the critical values -2.819<2.502<2.819
Lower bound:99.29, Upper bound:110.21. Because the 99% confidence interval includes 100, we do not reject the statement in the null hypothesis.
11.
Ho: \(\mu\) =67
Ha: \(\mu\) >67
There is a 0.02 probability of obtaining a sample mean of $73 or higher from a population whose mean is $67. So, if we obtained 100 simple random samples of size n=40 from a population whose mean is $67, we would expect about 2 of these samples to result in smaple means of $73 or higher.
Because the P-value is low 0.02<0.05, we reject the statement in the null hypothesis. There is sufficient evidence to conclude that the mean dollar amount withdrawn from a PayEase ATM is more than the mean amount from a standard ATM.
13.
Ho: \(\mu\) =22
Ha: \(\mu\) >22
The sample is random. The sample size is large, n=200 >30. We can reasonably assume that the sample is small relative to the population, so the scores are independent.
t0=2.176 > t0.05=1.660
There is sufficient evidence to conclude that students who complete the core curriculum are scoring above 22 on the math portion of the ACT.
15.
t0=-4.553 < -t0.01=-2.718
There is sufficient evidence to conclude that the mean hippocampal volume in alcoholic adolescents is less than the normal mean volume of 9.02 cm^3.
17.
t0=0.813 < t0.05=1.685
There is not sufficient evidence to conclude that the mean FICO score of high-income individuals is greater than that of the general population. In other words, it is not unlikely to ovtain a mean credit score of 714.2 or higher even though the true population mean credit score is 703.5.
19.
(35.44, 42.36)
Because the interval includes 40.7 years, there is not significant evidence to conclude that the mean age of a death-row inmate has changed since 2002.
1.
x^2 0.05=28.869
x^2 0.9 = 14.041
x^2 0.975 = 16.047; x^2 0.025 = 45.722
3.
x^2 0 = 20.496
x^2 0.95 = 13.091
Skip this problem
Do not reject the null hypothesis, because x^2 0 > x^2 0.95
13.
Note. The sample standard deviation of the data shown is.\(15.205043\). You will have to knit this to see the number though.
x^2 0 =6.422 > x^2 0.95=3.325
Do not reject the null hypothesis. There is not sufficient evidence to conclude that the standard deviation wait-time is less than 18.0 seconds.
15.
x^2 0=15.693 < x^2 0.90=15.659
Reject the null hypothesis. There is sufficient evidence to conclude that Rose is a more consistent player than other shooting guards in the NBA.