A researcher hypothesizes that children will like toys more if they make a noise (vs. if they do not make a noise). So the researcher creates two groups. In one group, children played with a toy that made noise. In a second group the children played with the same toy but it did not make noise. The time spent playing with each toy was recorded. The control group in this example is .

the group in which the toy did not make noise

Explanation:

In simple words, In a study, the control group serves as the benchmark against which evaluations are conducted. In a study when the impact of a therapy is unknown, assessments among the control group as well as the experimental unit are being utilized to evaluate the impact of the intervention a control group is commonly employed. They also have a striking resemblance to those in that experimental group or those who get the therapy.

answer; i do believe its (b) 12.5 years of age;

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