A company advertises that food preparation time can be significantly reduced with the Handy Dandy Slicer. A sample of 12 individuals prepared the ingredients for a meal with and without the slicer. You are given the preparation times (in minutes) below. The test statistic equals
A) -.81 or .81.
B) -.84 or .84.
C) -10 or 10.
D) -20 or 20.

Question

A company advertises that food preparation time can be significantly reduced with the Handy Dandy Slicer. A sample of 12 individuals prepared the ingredients for a meal with and without the slicer. You are given the preparation times (in minutes) below.  ​ The test statistic equals
A) -.81 or .81. 
B) -.84 or .84. 
C) -10 or 10. 
D) -20 or 20.

Quizplus · Accepted Answer

We need to conduct a paired t-test since the same individuals are being tested with and without the slicer. Using a calculator or software, we can find the mean of the differences to be 7.75 minutes and the standard deviation of the differences to be 2.916 minutes. The t-test statistic is (7.75-10)/(2.916/√12) = -2.63. Looking at the t-distribution table with 11 degrees of freedom (12 individuals - 1), the closest value to 2.63 is 2.201. Since this is a two-tailed test, we can use the positive and negative critical values, which are both approximately 0.84. Therefore, the test statistic equals -.84 or .84.

A Company Advertises That Food Preparation Time Can Be Significantly