Researchers have found that during the last recession, when income fell by 6 percent, many fast-food restaurants saw their sales increase by 8 percent while the sales of soda fell by 12 percent in grocery stores. what is the income elasticity of these groups of goods?

Income elasticity is obtained by dividing the percentage change in the quantity demanded of a product with by the percentage change in income. 

When income fell by 6 per cent and sales of many fast food restaurants increase by 8 per cent, then the income elasticity for fast food would be:

8/-6 = -1.33 

When income fell by 6 percent and sales of soda decreased by 12 percent, then the income elasticity for soda would be

-12/-6=2 

answer; coefficient of correlation;

answer; ///deficit;