a.) When p = $33, q = (343 - 33)^2/100 = 961 units.
q'(p) = -(343 - p) / 50
q'(33) = -(343 - 33)/50 = -6.2
Price elasticity of demand = price / quantity * q'(p) = 33/961 * -6.2 = -0.2129
b.) Revenue = quantity * price = p(343 - p)^2/100
For maximum revenue, dR/dp = 0
-2p(343 - p)/100 + (343 - p)^2/100 = 0
-686p + 2p^2 + 117649 - 686p + p^2 = 0
3p^2 - 1372p + 117649 = 0
p = 343 or p = 114.33
For maximum revenue, he should sell for $114.33
c.) Maximum Revenue = 114.33(343 - 114.33)^2 / 100 = $59,783