Answer:
 
      
The degrees of freedom are given by:
 
  
And the p value would be given by:
 
  
Since the p value is higher than the significance level of 0.05 we don't have enough evidence to conclude that the true mean is significantly higher than $300 because we FAIL to reject the null hypothesis.
Step-by-step explanation:
Information given
314 305 344 283 285 310 383 285 300 300
We can calculate the sample mean and deviation with the following formula:


 represent the sample mean
 represent the sample mean      
 represent the standard deviation for the sample
 represent the standard deviation for the sample      
 sample size
 sample size      
 represent the value to test
 represent the value to test
 represent the significance level
 represent the significance level
t would represent the statistic 
 represent the p value
 represent the p value 
Hypothesis to test
We want to verify if the true mean is greater than 300, the system of hypothesis would be:      
Null hypothesis: 
      
Alternative hypothesis: 
      
The statistic is given by:
 (1)
 (1)      
Replacing the info given we got:
 
      
The degrees of freedom are given by:
 
  
And the p value would be given by:
 
  
Since the p value is higher than the significance level of 0.05 we don't have enough evidence to conclude that the true mean is significantly higher than $300 because we FAIL to reject the null hypothesis.