A candy bar manufacturer is interested in trying to estimate how sales are influenced by the price of their product.  To do this, the company randomly chooses 6 small cities and offers the candy bar at different prices.  Using candy bar sales as the dependent variable, the company will conduct a simple linear regression on the data below:  City       Price ($) Sales River Falls 1.3 100 Hudson         1.6 90 Ellisworth 1.8 90 Prescott 2 40 Rock Elm 2.4 38 Stillwater 2.9 32  a. What is the estimated average change in the sales of the candy bar if price goes up $1.00?  b. What percent of the total variation in candy bar sales is explained by prices?