1. On May 18, 2020, the price of Royal Dutch Shell stock was $32.20. The interest rate was 1.5% per year. What was the implicit stock volatility (if any) implied by the prices below for call options expiring October 16? Draw a graph of your results. If you think you have found convergence, make sure that the implicit volatility is equal (to a tenth of a cent) in two consecutive iterations.

Strike Price	Market Price
20	13.85
22.5	10.60
27.5	8.40
30	4.80
32.5	3.61
35	2.35
37.5	1.50
40	0.875