Customers at costco spend an average of $130 per trip (the wall street journal, october 6, 2010). one of costco's rivals would like to determine whether its customers spend more per trip. a survey of the receipts of 25 customers found that the sample mean was $135.25. assume that the population standard deviation is $10.50 and that spending follows a normal distribution. use standard normal curve area table. a,specify the appropriate null and alternative hypotheses to test whether average spending at the rivals store is more than $130.b. calculate the value of the test statistic. c.calculate the p-value. d. calculate the critical value