SOLUTION: Sarah borrowed $6000, part at 15.5% and the rest at 14.25%. At the end of 3 years and 6 months, he had paid $3150 in simple interest. How much did he borrow at each rate?

Question 166704: Sarah borrowed $6000, part at 15.5% and the rest at 14.25%. At the end of 3 years and 6 months, he had paid $3150 in simple interest. How much did he borrow at each rate?
Answer by aswathytony(47) (Show Source): You can put this solution on YOUR website!
Amount borrowed = $6000
if she borrowed 'x' at 15.5% , rest is 6000 - x and borrowed at 14.25%
simple interest = p*n*r / 100 n = 3yrs + 6m = 3+ 1/2 yrs = 7/2 yrs
3150 = x * 7/2 * 15.5 /100 + (6000 - x ) * 7/2 * 14.25 /100
= 0.5425 x + (6000 -x) *0.4988
= 0.5425x + 6000 *0.4988 -0.4988x
= 0.0437 x + 2992.8
3150 -2992.8 = 0.0437 x
157.2 =0.0437x
x = 157.2/0.0437 = 3597.25
Amount she borrowed at 15.5% = $ 3597.25
Amount she borrowed at 14.25 % = 6000 - 3597.25
= $ 2402.75
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