SOLUTION: Melinda invested twice as much money in an
account paying 5% simple interest as she did in an account paying 3.5% simple interest. If her total interest at the end of 1 yr is $30
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account paying 5% simple interest as she did in an account paying 3.5% simple interest. If her total interest at the end of 1 yr is $30
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Question 1137096: Melinda invested twice as much money in an
account paying 5% simple interest as she did in an account paying 3.5% simple interest. If her total interest at the end of 1 yr is $303.75, find the amount she invested in the 5% account. Answer by ikleyn(52776) (Show Source):
Let x be an amount invested at 5%, the unknown value under the question.
Then the amount invested at 3.5% is the 0.5x dollars, according to the condition.
Your basic equation is THIS:
interest + interest = total interest
0.05*x + 0.035*(0.5x) = 303.75.
0.05x + 0.0175 = 303.75
0.0675x = 303.75 ====> x = = 4500.
Answer. $4500 was invested at 5% and half of that, $2250 dollars was invested at 3.5%.
Check. 0.05*4500 + 0.035*2250 = 303.75 dollars. ! Precisely correct !
You will find there different approaches (using one equation or a system of two equations in two unknowns), as well as
different methods of solution to the equations (Substitution, Elimination).
