2000 is invested in certificates of deposit Some of the 2000

$2000 is invested in certificates of deposit Some of the $2000 is placed in a 4% simple interest certificate of deposit and the rest in a 5% simple interest certificate of deposit. If at the end of the year, $88 was the total of the interest earned, how much was invested in the 5% certificate?

Solution

Let $ x be the amount invested in certificate of interest bearing 4 % simple interest. Then, the amount invested in the certificate bearing 5 % simple interest is $ 2000 - x. The interest for 1 year on the two certificates of deposit are x * 4/100 = 4x/100 and ( 2000 - x) * 5/100 = 5(2000 - x)/100 . Since the total interest for 1 year on the two certificates of deposit is $ 88, hence 4x/100 + 5(2000 - x)/100 . = 88 or, (4x +10000 - 5x)/ 100 = 88 or, ( 10000 - x) = 88* 100 = 8800 or, x = 10000 - 8800 = 1200. Then 2000 - x = 2000 - 1200 = 800. Thus, the amount invested in certificate of interest bearing 4 % simple interest is $ 1200 and the amount invested in certificate of interest bearing 5 % simple interest is $ 800.