Anational interest rate on houses for 25 years is 4.3%. a banker in a large northwestern city believes that the local interest rates are lower than the national rate. what is the null hypothesis that this banker wishes to test?

The national interest rate on houses for 25 years is 4.3%. The banker wishes to test that the local interest rates are lower than the national rate. So he should use the initial data of 4.3% interest as his base data. Then he should investigate the rates of houses in the local vicinities and compare it to his base data. 

The answer for this question is 80