Historically the average annual global temperature have been 13.5^oC. A sample of the previous 30 years has shown a mean annual temperature of 13.8^oC with a standard deviation of 0.83^oC. At a 5% level of significance, is there enough evidence to conclude that the average global temperature has been increased from 13.5^oC?

a) Properly state the hypothesis:

b) Calculate the p-value

c) Conclusion (must be mathematically justified)