Phyllis invested $11,500, a portion earning a simple interest rate of 1 1/4% per year and the rest earning a rate of 1% per year. After....?

Phyllis invested $11,500, a portion earning a simple interest rate of 

1 1/4% per year and the rest earning a rate of 1% per year. After one year the total interest earned on these investments was $136.25. How much money did she invest at each rate?

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  • Alvin
    Lv 4
    1 month ago
    Favourite answer

    let x = amount invested at 1 1/4 % 

    11500-x = amount invested at 1 % 

    1.0125x + (11500-x)1.01 = 11500+ 136.25  

    0.0025x  + 11500*1.01 =  11636.25 

    0.0025x  + 11615  = 11636.25 

    0.0025x  = 11636.25 -11615 =   21.25 

    x = 21.25/ .0025 =    8500

    x =8500  

    11500 -8500 = 3000

    8500  at 1 1/4 % 

    and 

    3000  at 1% 

    8500*1.0125  + 3000*1.01 =  11636.25

    (it checks) 

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