Refer to given problem. Give a 90% confidence interval for the difference in average occupancy rates at the Westin Plaza hotel before and after the advertising.

Problem
The senior vice president for marketing at Westin Hotels believes that the company's recent advertising of the Westin Plaza in New York has increased the average occupancy rate at that hotel by at least 5%. To test the hypothesis, a random sample of daily occupancy rates (in percentages) before the advertising is collected. A similar random sample of daily occupancy rates is collected after the advertising took place. The data are as follows.

Before Advertising(%):

86,92,83,88,79,81,90,76,80,91,85,89,77,91,83

After Advertising(%) :
88,94,97,99,89,93,92,98,89,90,97,91,87,80,88,96

Assume normally distributed populations of occupancy rates with equal population variances. Test the vice president's hypothesis.