The owner of a local health food store recently started a new ad campaign to attract more business and wants to test whether average daily sales have...

The owner of a local health food store recently started a new ad campaign to attract more business and wants to test whether average daily sales have increased. Historically average daily sales were approximately $2,700. After the ad campaign, the owner took a random sample of forty-five days and found that daily average sales had increased to $2,984. What is store owner's null hypothesis?

(please provide explanations)