Answer:

The degrees of freedom are given by:

Now we can calculate the p value with this probability:
 And for this case the p value is lower than the significance level and the best conclusion would be:
 And for this case the p value is lower than the significance level and the best conclusion would be:
The p-value is 0.0018. We reject H0 at the 5% significance level because the p-value 0.0018 is less than 0.05. 
Explanation:
Information given
 sample size
 sample size 
 represent the value to check
 represent the value to check
 represent the significance level
 represent the significance level 
 represent the p value
 represent the p value 
Hypothesis to verify
We want to verify if the true mean for this case is lower than 3.5, the system of hypothesis would be: 
Null hypothesis:
 
 
Alternative hypothesis:
 
 
The statistic is given by:
 (1)
 (1) 
For this case the statistic is given by:

The degrees of freedom are given by:

Now we can calculate the p value with this probability:
 And for this case the p value is lower than the significance level and the best conclusion would be:
 And for this case the p value is lower than the significance level and the best conclusion would be:
The p-value is 0.0018. We reject H0 at the 5% significance level because the p-value 0.0018 is less than 0.05.