Answer:
The hippocampus volumes in the alcoholic adolescents are less than the normal volume of 9.02 cm³
Step-by-step explanation:
Let x= the hippocampus volumes in the alcoholic adolescents
We'll conduct a hypothesis test at the 0.01 significance level with
Null hypothesis: x = 9.02 cm³
Alternate hypothesis: x < 9.02 cm³
A sample of 13 alcoholic adolescents gives the parameters
size=N= 13
mean=M= 8.12 cm³
standard deviation= s= 0.8 cm³
According to the sample, with 99% confidence, t statistic for the value X=9.02 can be found using the formula:
t= where
- M is the sample mean (8.12)
- s is the standard deviation of the sample (0.8)
- N is the sample size (13)
If we put these numbers in the formula:
t= =4.056
One tailed critical value for the sample with 12 degrees of freedom (sample size-1) in 99% confidence level is 2.681.
Since t value (4.056) is bigger than the critical value, we fail to reject the alternate hypothesis, therefore reject the null hypothesis and accept alternate hypothesis.