Do strong El Nino phenomena change the weather as much as people claim? a. Using the data

Question:

Do strong El Nino phenomena change the weather as much as people claim?
a. Using the data in the following table (aggregate temperature departures from spring norms in degrees Celsius), test the claim that the progression of a strong El Nino, from the spring of onset to the next spring, affects Canadian temperature departures from seasonal norms. Use a 0.05 level of significance.
b. Construct a 95% confidence interval for the mean difference of the "onset" minus "second spring" departures from norms. Write a statement that interprets the resulting confidence interval.