Fortune Brands Home & Security, Inc.sells Master Lock padlocks. It reported an increase in net sales from $4.0 billion in 2011 to $4.3 billion in 2012, and an increase in gross profit from $1.2 billion in 2011 to $1.4 billion in 2012 a. Calculate each year's gross profit percentage. (Round your answers to 1 decimal place.) 2012 2011 Gross Profit Percentage b. Determine whether the change in gross profit was caused by. an increase in gross profit per sale an increase in sales volume. an increase in gross profit per sale and sales volume