Studies indicate that excessive noise at night can affect weight gain. One study of n = 127 rats compared the weight gain of rats exposed to excessive noise at night and the weight gain of rats in a quiet night environment. Sample statistics for the study are given in the table below. Use this information to determine if there is significant evidence that weight gain of rats exposed to excessive noise at night is different on average than weight gain of rats in a quiet night environment. Excessive noise at night environment (Group 1) Quiet night environment (Group 2) Sample mean (grams) 22.4 19.9 Sample standard deviation (grams) 6.4 3.8 Observations/Sample size 69 58 There were 127 rats used for this study but the degrees of freedom used for the test was 57. In one or two sentences explain how the degrees of freedom was calculated.
Studies indicate that excessive noise at night can affect weight gain. One study of n = 127 rats compared the weight gain of rats exposed to excessive noise at night and the weight gain of rats in a quiet night environment. Sample statistics for the study are given in the table below. Use this information to determine if there is significant evidence that weight gain of rats exposed to excessive noise at night is different on average than weight gain of rats in a quiet night environment.
|
|
Excessive noise at night environment (Group 1) |
Quiet night environment (Group 2) |
|
Sample mean (grams) |
22.4 |
19.9 |
|
Sample standard deviation (grams) |
6.4 |
3.8 |
|
Observations/ |
69 |
58 |
|
|
||
There were 127 rats used for this study but the degrees of freedom used for the test was 57. In one or two sentences explain how the degrees of freedom was calculated.
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