SOLUTION: Marcia has $18000 to invest in two different investments. She invest $10000 at 4% yearly interest in one investment .At what rate must she invest the remainder so that she earns a

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Question 1111083: Marcia has $18000 to invest in two different investments. She invest $10000 at 4% yearly interest in one investment .At what rate must she invest the remainder so that she earns a yearly interest of more than $700
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
For 4% annual interest investment:
(1) +I%5B1%5D+=+P%5B1%5D%2Ar%5B1%5D%2At+
(1) +I%5B1%5D+=+10000%2A.04%2A1+
(1) +I%5B1%5D+=+400+
For the 2nd investment:
(2) +I%5B2%5D+=+P%5B2%5D%2Ar%5B2%5D%2At+
(2) +I%5B2%5D+=+8000%2Ar%5B2%5D%2A1+
----------------------------------
(3) +I%5B1%5D+%2B+I%5B2%5D+%3E+700+
(3) +400+%2B+I%5B2%5D+%3E++700+
(3) +I%5B2%5D+%3E+300+
----------------------------------
From (2):
+8000r%5B2%5D+%3E+300+
+r%5B2%5D+%3E+3%2F80+
+r%282%29+%3E+.0375+
The remainder must be invested at a rate
greater than 3.75%