Answer:
$2000 was invested at 5% and $5000 was invested at 8%.
Step-by-step explanation:
Assuming the interest is simple interest.
<u>Simple Interest Formula</u>
I = Prt
where:
- I = interest earned.
- P = principal invested.
- r = interest rate (in decimal form).
- t = time (in years).
Given:
- Total P = $7000
- P₁ = principal invested at 5%
- P₂ = principal invested at 8%
- Total interest = $500
- r₁ = 5% = 0.05
- r₂ = 8% = 0.08
- t = 1 year
Create two equations from the given information:
![\textsf{Equation 1}: \quad \sf P_1+P_2=7000](https://tex.z-dn.net/?f=%5Ctextsf%7BEquation%201%7D%3A%20%5Cquad%20%5Csf%20P_1%2BP_2%3D7000)
![\textsf{Equation 2}: \quad \sf P_1r_1t+P_2r_2t=I\implies 0.05P_1+0.08P_2=500](https://tex.z-dn.net/?f=%5Ctextsf%7BEquation%202%7D%3A%20%5Cquad%20%5Csf%20P_1r_1t%2BP_2r_2t%3DI%5Cimplies%200.05P_1%2B0.08P_2%3D500)
Rewrite Equation 1 to make P₁ the subject:
![\implies \sf P_1=7000-P_2](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%20P_1%3D7000-P_2)
Substitute this into Equation 2 and solve for P₂:
![\implies \sf 0.05(7000-P_2)+0.08P_2=500](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%200.05%287000-P_2%29%2B0.08P_2%3D500)
![\implies \sf 350-0.05P_2+0.08P_2=500](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%20350-0.05P_2%2B0.08P_2%3D500)
![\implies \sf 0.03P_2=150](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%200.03P_2%3D150)
![\implies \sf P_2=\dfrac{150}{0.03}](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%20P_2%3D%5Cdfrac%7B150%7D%7B0.03%7D)
![\implies \sf P_2=5000](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%20P_2%3D5000)
Substitute the found value of P₂ into Equation 1 and solve for P₁:
![\implies \sf P_1+5000=7000](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%20P_1%2B5000%3D7000)
![\implies \sf P_1=7000-5000](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%20P_1%3D7000-5000)
![\implies \sf P_1 = 2000](https://tex.z-dn.net/?f=%5Cimplies%20%5Csf%20P_1%20%3D%202000)
$2000 was invested at 5% and $5000 was invested at 8%.
Learn more about simple interest here:
brainly.com/question/27743947
brainly.com/question/28350785