Dermody Snow Removal's cost formula for its vehicle operating cost is $3,070 per month plus $337 per snow-day. For the month of December, the company planned for activity of 19 snow-days, but the actual level of activity was 21 snow-days. The actual vehicle operating cost for the month was $9,755. The spending variance for vehicle operating cost in December would be closest to:

Studies show that massage therapy has a variety of health benefits and it is not too expensive. a sample of 12 typical one-hour massage therapy sessions showed an average charge of $58. the population standard deviation for a one-hour session is =$5.55. a. what assumptions about the population should we be willing to make if a margin of error is desired? (select your the population has uniform distribution/ the population is at least approximately normal is required/ the population has no exponential distribution/ no assumptions should be made) b. using 90% confidence, what is the margin of error (to 2 decimals) c. using 99% confidence, what is the margin of error (to 2 decimals)