8.A certain sum of money is invested at 10%. Twice that amount is invested at 8%. The total amount of inter

Question

A certain sum of money is invested at 10%. Twice that amount is invested at 8%. The total amount of interest from both investments is $91. How much is invested at 8%.

Solution please?

Answer 1

Simple interest = (P*n*R/100)
P=Principal amount
n= peiod in years
R= Rate of interest

Let initial amount $x
Assume the period to be 1 year
Interest = x*1*10/100 = x/10
ASecond amount = $2x
Interest = 2x*1*8/100 = 16x/100
Total interest = 26x/100 = $91
x = 91*100/26 = 7*50 = $350
Thus principal at 8% = 2*350 = $700

Answer 2

Ok, the total amount invested is $1,050, out of that, $ 700 was invested at 8% and $ 350 at 10%

$ 350 @ 10% = $ 35 in interest
$ 700 @ 8% = $ 56 in interest
SUM
$ 350 + $ 750 = $ 1,050
$ 35 + $ 56 = $ 91

Answer 3

x = amount invested at 10% interest 2x = amount invested at 12% 2x - P5000 = amount invested at 8% 0.10(x) + 0.12(2x) + 0.08(2x - P5000) = P4350 0.10x + 0.24x + 0.16x - P400 = P4350 0.50x - P400 = P4350 0.50 = P4750 x = P9500 invested at 10%: x = P9500 invested at 12%: 2x = 2*P9500 = P19,000 invested at 8%: 2x - P5000 = P19,000 - P5000 = P14,000

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