Week 4 Practice Worksheet
Provide a response to the following questions.
Note: Each team member should compute the following questions and submit to the Learning Team forum. The team should then discuss each team member’s answers to ascertain the correct answer for each question. Once your team has answered all the questions, submit a finalized team worksheet.

  1. Two boats, the Prada (Italy) and the Oracle (USA), are competing for a spot in the upcoming America’s Cup race. They race over a part of the course several times. The sample times in minutes for the Prada were as follows: 12.9, 12.5, 11.0, 13.3, 11.2, 11.4, 11.6, 12.3, 14.2, and 11.3. The sample times in minutes for the Oracle were as follows: 14.1, 14.1, 14.2, 17.4, 15.8, 16.7, 16.1, 13.3, 13.4, 13.6, 10.8, and 19.0. For data analysis, the appropriate test is the t test: two-sample assuming unequal variances.

The next table shows the results of this independent t test. At the .05 significance level, can you conclude that there is a difference in their mean times? Explain these results to a person who knows about the t test for a single sample but who is unfamiliar with the t test for independent means.

Hypothesis Test: Independent Groups (t test, unequal variance)
Prada Oracle
12.170 14.875 mean
1.056 2.208 std. dev.
10 12 n
16 df
-2.7050 difference (Prada – Oracle)
0.7196 standard error of difference
0 hypothesized difference
-3.76  t
.0017  p-value (two-tailed)
-4.2304 confidence interval 95.% lower
-1.1796 confidence interval 95.% upper
1.5254 margin of error