The Mean Length of a Candy Bar Is 43 Millimeters

question 52

Multiple Choice

The mean length of a candy bar is 43 millimeters. There is concern that the settings of the machine cutting the bars have changed. Test the claim at the 0.02 level that there has been no change in the mean length. The alternate hypothesis is that there has been a change. Twelve bars (n = 12) were selected at random and their lengths recorded. The lengths are (in millimeters) 42, 39, 42, 45, 43, 40, 39, 41, 40, 42, 43, and 42. The mean of the sample is 41.5 and the standard deviation is 1.784. Computed t = -2.913. Has there been a statistically significant change in the mean length of the bars?

• A) Yes, because the computed t lies in the rejection region.
• B) No, because the information given is not complete.
• C) No, because the computed t lies in the area to the right of -2.718.
• D) Yes, because 43 is greater than 41.5.

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Definitions:

Mental Process

The internal operations of the mind that include thinking, feeling, and decision-making.

Self-Correcting Process

A mechanism or system that is designed to identify and correct errors or deviations from a desired state or norm automatically.

Manipulates Factors

To control or alter variables or components in an experimental setting to determine their effects on an outcome.

Experiment

A method of testing hypotheses by observing the outcomes of controlled conditions.