Question | Answer |
a. 90% | |
b. 95% | |
c. 99% |
Question | Answer |
a. What is the point estimate of μ? Round to two decimal places. | |
b. Calculate a 95% confidence interval for μ.What are the lower and upper limits? Round to two decimal places. | Lower
Upper |
c. What is the margin of error? Round to two decimal places. |
Question | Answer |
a. E = 2.3, σ = 15.40, confidence level = 99%. Round to the nearest whole number. | |
b. E = 4.1, σ = 23.45, confidence level = 95%. Round to the nearest whole number. | |
c. E = 25.9, σ = 122.25, confidence level = 90%. Round to the nearest whole number. |
Question | Answer |
a. The null hypothesis is a claim about a population parameter that is assumed to be false until it is declared false. | |
b. An alternative hypothesis is a claim about a population parameter that will be true if the null hypothesis is false. | |
c. The significance level, denoted by α, is the probability of making a Type II error, that is, the probability of rejecting the null hypothesis when it is actually true. | |
d. The nonrejection region is the area to the right or left of the critical point where the null hypothesis is not rejected. | |
e. Thelevelofsignificanceinatestofhypothesisistheprobabilityofmakinga Type III error.ItistheareaundertheprobabilitydistributioncurvewherewerejectHo. |
n1 =650 ¯x1 =1.05 σ1 =5.22
n2 =675 ¯x2 =1.54 σ2 =6.80
Question | Answer |
a. In selecting which version of the z/t test of means to use, consider the sample size and whether you are given the population or sample standard deviations. Given the data above, will you use a z or t test? | |
b. What is the value of z? Round to two decimal places. | |
c. Would you reject the null hypothesis? YES or NO |
Question | Answer |
a. Let μ1 and μ2 be the average credit card debts for all such households for the years 2014 and 2013, respectively. What is the point estimate of μ1 − μ2? Round to two decimal places. Do not include the dollar sign. | |
b. Construct a 98% confidence interval for μ1 − μ2. Do not include the dollar sign. What are the lower and upper bounds? Round to two decimal places. | Lower
Upper |
c. Using a 1% significance level, can you conclude that the average credit card debt for such households was higher in 2014 than in 2013? Use both the p-value and the critical-value approaches to make this test.
Reject Ho OR Do not reject Ho |
Gamma Corporation wants to estimate the mean difference in fuel consumption with a margin of error of 2 mpg at the 95% confidence level.Assume that the differences in fuel consumption are normally distributed. Previous studies suggest that 3 mpg is a reasonable estimate of the standard deviation. Use this formula to determine the sample size: n = z2 σ2/E2(example 8-3, p. 321).
Question | Answer |
How many cars should be tested? Round up to the next whole number. |