Records of 40 used passenger cars and 40 used pickup trucks (none used commercially) were randomly selected to investigate whether there was any difference in the mean time in years that they were kept by the original owner before being sold. For cars the mean was 5.3 years with standard deviation 2.2 years. For pickup trucks the mean was 7.1 years with standard deviation 3.0 years. Test the hypothesis that there is a difference in the means against the null hypothesis that there is no difference. Use the 5% level of significance.
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The null hypothesis states that there is no difference in the mean time in years that passenger cars and pickup trucks were kept by the original owner before being sold. The alternative hypothesis states that there is a difference. Null hypothesis (H0): μ1 = Show more…
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Records of 40 used passenger cars and 40 used pickup trucks (none used commercially) were randomly selected to investigate whether there was any difference in the mean time in years that they were kept by the original owner before being sold. For cars the mean was 5.3 years with standard deviation 2.2 years. For pickup trucks the mean was 7.1 years with standard deviation 3.0 years. Test using the 1% level of significance. H0: ______ Ha: ____ In words, define the random variable. The distribution to use for the test is _____________. Calculate the test statistic using your data. Draw a graph and label it appropriately. Calculate the p-value. Do you reject or not reject the null hypothesis? Why? Write a clear conclusion using a complete sentence.
Sri K.
One year the mean age of an inmate on death row was 39.9 years a sociologist wondered whether the mean age of a death row inmate has changed since then she randomly selects 32 Deathrow inmates and find other mean age is 38.5 with a standard deviation of 9.3 construct a 95% confidence interval about the mean age what is the interval imply additionally, find the alternative and null hypothesis.
Ahmet Y.
In a recent year the fuel economy of all passenger vehicles was $19.8 \mathrm{mpg}$. A trade organization sampled 50 passenger vehicles for fuel economy and obtained a sample mean of 20.1 mpg with standard deviation $2.45 \mathrm{mpg}$. The sample mean 20.1 exceeds $19.8,$ but perhaps the increase is only a result of sampling error. a. Perform the relevant test of hypotheses at the $20 \%$ level of significance using the critical value approach. b. Compute the observed significance of the test. c. Perform the test at the $20 \%$ level of significance using the $p$ -value approach. You need not repeat the first three steps, already done in part (a).
Testing Hypotheses
The Observed Significance of a Test
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