### Home > CCA2 > Chapter 11 > Lesson 11.2.3 > Problem 11-65

Students in Miss Hampton’s science class tested the effectiveness of detergent in getting dishes clean. They started by weighing each plate. Then they created a gooey paste of hard-to-clean foods (spaghetti sauce, mustard, mashed potatoes, peanut butter, and grape jelly) and smeared

What is the difference in the proportions (detergent minus plain water)? Express your answer as a decimal.

Mrs. Hampton’s class ran a computer simulation and determined the sample-to-sample variability of the

*difference*between the proportion of food removed by the detergent compared to plain water. They concluded that the*difference*in the true proportion of food removed was. Is a difference of zero a plausible result considering their margin of error? What does a difference of zero mean in the context of this problem?

What is

Adifference indicates that there is ... Are you convinced that there is a true difference between cleaning with detergent and cleaning with plain water?

Is a difference of

within the margin of error from part (b)?