The demand equation for blue jeans in the U. S. is QD = 500 - 7P, and the supply equation for blue jeans is QS = 20 + 3P, where P is the price per pair of blue jeans and QD and QS are in 1,000’s of blue jeans.
(A) How many blue jeans are purchased and at what price do they sell for in the U. S.?

Sales at a fast-food restaurant average $6,000 per day. the restaurant decided to introduce an advertising campaign to increase daily sales. to determine the effectiveness of the advertising campaign, a sample of 49 days of sales were taken. they found that the average daily sales were $6,300 per day. from past history, the restaurant knew that its population standard deviation is about $1,000. if the level of significance is 0.01, have sales increased as a result of the advertising campaign? multiple choicea)fail to reject the null hypothesis.b)reject the null hypothesis and conclude the mean is higher than $6,000 per day.c)reject the null hypothesis and conclude the mean is lower than $6,000 per day.d)reject the null hypothesis and conclude that the mean is equal to $6,000 per day.expert answer