posted by Lisa .
Through extensive research, Metlife Insurance claims that the mean footwell intrusions for Toyota Corrola and Toyota Rav4 are equal. Crash test at 40mph were performed at 7 randomly selected Toyota Corrola and 13 randomly Toyota Rav4s selected. The amount that the footwell intruded on the driver's side was measured. The mean footwell intrusion for Toyota Corrola was 11.8 centimeters with a standard deviation of 4.53. The mean footwell intrusion for Toyota Rav4was 9.52 centimeters with a standard deviation of 3.84. At a=0.01 can you reject the insurance claim? Assume the population variances are samples. (Independent Samples)
Try an independent groups t-test.
Ho: µ1 = µ2 -->population means are equal
Ha: µ1 does not equal µ2 -->population means are not equal
Use (n1 + n2 - 2) degrees of freedom for this test. Use a t-table to determine your cutoff or critical value to reject the null using 0.01 level of significance for a two-tailed test. If your test statistic exceeds the critical values from the table, reject the null and conclude a difference (µ1 does not equal µ2). If the test statistic does not exceed the critical values from the table, do not reject the null.
I hope this will help get you started.