When seeking to determine the number of shirts made by employees subjected to noise with and without the use of headphones, the independent variable is the amount of noise.
Explanation:
During an investigation, the independent variable may be subject to change, in order to observe the effect it will have on the dependent variable.
In the case presented, the amount of noise to which employees are exposed represents the independent variable, which is modified by the use of headphones that block all or part of the noise.
The productivity —expressed in the number of shirts made— can be expected to be higher for employees not exposed to noise.
Other options do not apply because:
<u><em>The number of shirts made by the employee</em></u><em>. Dependent variable
.</em>
<u><em>The type of music the employees listen to while they work or the amount of training employees need</em></u><em>. These are not the variables studied.</em>
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