For each of the next five days, Mary plans to spend $\frac{1}{3}$ of the money she has at the beginning of the day. At the beginning of the first day, Mary has $\$243$. Assuming that Mary doesn't get any new money over the next five days, how much money will she have after the fifth day?

 Jan 21, 2020

This is a compound interest problem in a way, so we have 1/3 being the "interest". Since there are five times 1/3 is applied to the previous total, we can form the equation (1/3)^5 * 243 = (1/243) * 243 = 1.

 Jan 21, 2020

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