4. Joe's BBQ Palace sells barbecue plates for $4.50 each, and serves an average of 525 customers per week. During a recent promotion, Joe cut his price to $3.50 and observed an increase in sales to 600 plates per week. a. Calculate J oe's arc price elasticity of demand. b. Joe is considering permanently lowering his price to $4.00 to increase revenue. How many plates should Joe expect to sell at the new price? (Use the elasticity value you calculated in 'a' above). Does the move make sense in light of J oe's desire to increase revenue