Answer:
23.1 years (nearest tenth)
Explanation:
Compound Interest Formula
![\large \text{$ \sf A=P\left(1+(r)/(n)\right)^(nt) $}](https://img.qammunity.org/2023/formulas/mathematics/college/a2h2k73eemgbrq3rhqgu7istzwptcok98e.png)
where:
- A = final amount
- P = principal amount
- r = interest rate (in decimal form)
- n = number of times interest applied per time period
- t = number of time periods elapsed
Given:
- A = $1200
- P = $600
- r = 3% = 0.03
- n = 12 (as compounded monthly)
- t = years
Substitute the given values into the formula and solve for t:
![\implies \sf 1200=600\left(1+(0.03)/(12)\right)^(12t)](https://img.qammunity.org/2023/formulas/mathematics/college/ib07x2meonvovn42vghdae3nrew4tw7y0d.png)
![\implies \sf 1200=600\left(1.0025\right)^(12t)](https://img.qammunity.org/2023/formulas/mathematics/college/i42h7gw75gxs7quxgwkg4w3xqdbjm6r4vy.png)
![\implies \sf (1200)/(600)=\left(1.0025\right)^(12t)](https://img.qammunity.org/2023/formulas/mathematics/college/2lb99yih6646wbzu7r1svazeiteqi31otn.png)
![\implies \sf 2=\left(1.0025\right)^(12t)](https://img.qammunity.org/2023/formulas/mathematics/college/6yo6qo1gqwx86woir5afgog6um0hv04bwm.png)
Take natural logs:
![\implies \sf \ln 2=\ln \left(1.0025\right)^(12t)](https://img.qammunity.org/2023/formulas/mathematics/college/z38ilgbs3w7tob5jbhn4qzp548mrwkjxt5.png)
![\implies \sf \ln 2=12t\ln \left(1.0025\right)](https://img.qammunity.org/2023/formulas/mathematics/college/2xipn1ublfw7yfors5ij9ofqj77w5fjy5c.png)
![\implies t=( \ln 2)/(12 \ln (1.0025))](https://img.qammunity.org/2023/formulas/mathematics/college/znxx413g7gzw1msqkz36187j34odh0wtun.png)
![\implies t=23.13377513...](https://img.qammunity.org/2023/formulas/mathematics/college/s8z8gpdxxwrm0g8eehyc0yqd4urylsfzer.png)
![\implies t=23.1\: \sf years \:\:(nearest\:tenth)](https://img.qammunity.org/2023/formulas/mathematics/college/yqw2gpf37hk9dps3nmrfdd0n9z7bpr9ry3.png)
The money will double in value in approximately
years.