Two sisters each open IRAs in 2011 and plan to invest $3,000 per year for the

next 30 years. Mary makes her first deposit on January 1, 2011, and will make all

future deposits on the first day of the year. Jane makes her first deposit on

December 31, 2011, and will continue to make her annual deposits on the last day

of each year. At the end of 30 years, the difference in the value of the IRAs

(rounded to the nearest dollar), assuming an interest rate of 7% per year, will be....

I think it is $210 but I saw an answer online that said $19,837. How am I so off?