Applied Retail Research Question - Probability HELP

So being a business student, I haven't taken many stats courses. I barely remember the stats i took in high school and now im having to deal with a course that is bombing me with stats problems. I dont get what to do? Which formulas to compute with? Please help. any help is much appreciated. thanks.

QUESTION 2 (20)

A retailer operates in both Ontario and Quebec. The 45 stores in Ontario report an average daily sale of $25,000 with a standard deviation of $5000 where as the 35 stores in Quebec report a daily average sale of $24,000 with a standard deviation of $1,000.

At the company's annual general meeting the mangers from Quebec were concerned about the claims made by the managers from Ontario that Ontario stores performed better because of the higher average daily sales. The VP Sales has asked you to determine if the difference in average sales is statistically significant assuming that the sales variance in both provinces is unequal.

Please undertake the analysis of comparing mean sales and advise the VP Sales on the statistical significance of the difference in sales.

QUESTION 3 (20)

A retailer has approached you for a survey of customers that have made purchases in the past four months at the store. The retailer would like to learn more about the buying habits of new patrons. You have designed a survey that you'd like to administer to customers who have made recent purchases.

You would first like to determine the sample size. The average purchase per customer is $75 and the standard deviation is $35. You would prefer a relative level of precision of 5% and your answer to be valid 95% of the time. Determine the sample size.

The critical value of t(alpha/2) is 1.96 for 95% confidence level.