I'll appreciate if you help me solving this question pls!

One way to know the efficiency of international airports is to measure the percentage of flights that leave the airport on time on a daily basis. From a random sample of 100 days, it was found that an average of 81.5% of flights leave YVR (Vancouver International Airport) on time and a standard deviation of 4.5%. From past experience, it is known that the percentage of flights that leave YVR on time has a Normal distribution. a) Provide a description of the parameter of interest in this study. [2 marks] b) Construct a 98% confidence interval of the parameter in part (a). [3 marks]