Assume that in 2018, a copper penny struck at the Philadelphia mint in 1793 was sold for $270,000. What was the rate of return on this investment? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Rate of return % Assume that in 2018, a copper penny struck at the Philadelphia mint in 1793 was sold for $270,000. What was the rate of return on this investment? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Rate of return %