Hi there! To find the rate of decay, we should divide the percentage each year by 12, because there are 12 months in 1 year and it decays by 6% in that amount of time. 6% (0.06) / 12 is 0.005. Multiply that by by 100 to put in in percentage form and it is 0.5. Or, you could just divide 6 by 12 to get 0.5. The rate of decay each month is 0.5%. The answer is D: -0.5%.
