In 2013, In and Out charged $6.50 for a hamburger and sold 3,000,000 of them. In 2016, although In and Out raised the price to $8.00, sales of his burgers rose to 4,000,000. Use the concepts of a shift in the demand curve versus a movement along the demand curve to explain why this increase in sales does not represent a violation of the law of demand. Provide examples and details that explain this occurrence.