(I know how to solve this question for mean > 38.3 OR mean <38.3, but here, I have a problem with the alternative hypothesis where it says mean IS NOT equal to 38.3, how should I show it in P(Ha)? I normally start with Mean> OR < 38.3 and convert it to Z or in this case T, but this, I don't know how to tackle it)

The ventricle is the cavity in the brain. The mean volume of ventricles in the healthy

elderly is 38.3 cm3. We know that the ventricular volume is normally distributed. To inspect

the volume of ventricle as a biomarker for Alzheimer's disease, we collected the ventricular

volumes of 25 Alzheimer's disease patients. If their sample mean was 49.9 cm3 with a sample

standard deviation of s=25.3 cm3. Can we conclude that the mean ventricular volume of

Alzheimer's disease patients is not equal to 38.3 cm3? Use the significance level of 5%