Answer:
 
  
The degrees of freedom are given by:

Since is a two-sided test the p value would be:  
 
  
Since the p value is a very low value we have enough evidence to conclude that true mean is significantly different from 1.35 in/year at any significance level commonly used for example ( ).
). 
Step-by-step explanation:
Data given and notation  
 represent the sample mean
 represent the sample mean 
 represent the sample deviation
 represent the sample deviation
 sample size
 sample size  
 represent the value that we want to test
 represent the value that we want to test  
 represent the significance level for the hypothesis test.
 represent the significance level for the hypothesis test.  
t would represent the statistic (variable of interest)  
 represent the p value for the test (variable of interest)
 represent the p value for the test (variable of interest)  
State the null and alternative hypotheses.  
We need to conduct a hypothesis in order to check if the true mean is different from 1.35 in/year, the system of hypothesis would be:  
Null hypothesis: 
  
Alternative hypothesis: 
  
The statistic is given by:
 (1)
 (1)  
Calculate the statistic  
We can replace in formula (1) the info given like this:  
 
  
P-value  
The degrees of freedom are given by:

Since is a two-sided test the p value would be:  
 
  
Since the p value is a very low value we have enough evidence to conclude that true mean is significantly different from 1.35 in/year at any significance level commonly used for example ( ).
).