Question 706791
20,000 is invested at 5 %, so in one year, you will earn 20000*0.05 = 1000 dollars in interest



1000 dollars is 5% of the total amount invested, but we want a 4.8% yield.


Investing an additional x dollars at 4% yields 0.04x dollars after one year.


You have invested 20000 + x dollars total


You earn 1000 + 0.04x dollars in interest alone.


The ratio of interest earned to amount invested is: (1000 + 0.04x)/(20000 + x)


This ratio must be equal to 0.048 (the decimal equivalent of 4.8%) since this is your requirement


So we can say


(1000 + 0.04x)/(20000 + x) = 0.048



I'll let you solve for x.