Last year, Karen opened an investment account with $8400. At the end of the year, the amount in the account had increased by 6.5%. How much is this increase in dollars? How much money was in her account at the end of last year?
Increase in amount: $
Year-end amount: $
To calculate the increase in dollars, we need to multiply the initial amount by the percentage increase: $8400 * 6.5% = $<<8400*6.5*.01=546>>546.
So, the increase in dollars is $546.
To calculate the year-end amount, we need to add the increase to the initial amount: $8400 + $546 = $<<8400+546=8946>>8946.
Thus, the amount of money in Karen's account at the end of last year was $8946. Answer: \boxed{546}.