Statistics Hypothesis testing?

You are a statistician at a local television station, and you have been asked to evaluate the performance of the meteorological team (i.e. the weather people). You obtain temperature measurements for actual high and low temperatures and the predicted high and low temperatures for 31 randomly selected days from the current year. Using the data to support your evaluation, answer the following questions regarding the accuracy of temperature prediction by the meteorological team.

1). Evaluate the weather team's ability to accurately predict low temperatures. Using the appropriate hypothesis test, is there sufficient evidence that a predicted temperature will, on average, differ from the actual temperature? (Hint: Create another variable DLOW = Predicted Low - Actual Low. If there is, on average, no significant difference between predicted and actual low temperatures, what should the mean DLOW equal?)

What hypothesis test should I use?