From Past Records It Is Known That the Average Life

question 51

Multiple Choice

From past records it is known that the average life of a battery used in a digital clock is 305 days. The battery life is normally distributed. The battery was recently modified to last longer. A sample of 20 of the modified batteries was tested. It was discovered that the mean life was 311 days and the sample standard deviation was 12 days. We want to test at the 0.05 level of significance whether the modification increases the life of the battery. What is our decision rule?

• A) Do not reject the null hypothesis if computed t is 1.96 or greater
• B) Reject the null hypothesis if computed t is less than 1.96
• C) Do not reject the null hypothesis if computed t is 1.729 or greater
• D) Reject the null hypothesis if computed t is 2.086 or greater
• E) Reject the null hypothesis if the computed t is 1.729 or greater

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Definitions:

Electromyography (EMG)

The insertion of needles into selected skeletal muscles for the purpose of recording nerve conduction time in relation to muscle contraction.

Electrical Activity

The movement or flow of electrical charges, often referring to physiological processes in the body.

Peripheral Muscles

Muscles located in the outer regions of the body, as opposed to those central to the core or trunk.

Voluntary Function

Actions or processes in the body controlled by an individual's conscious decision.