Question 221018


{{{A=P+Prt}}} Start with the simple interest formula.



{{{4000=2000+2000*0.05*t}}} Plug in {{{A=4000}}} (double of the initial investment of $2000), {{{P=2000}}}, and {{{r=0.05}}} (the decimal equivalent of 5%).



{{{4000=2000+100*t}}} Multiply {{{2000}}} and {{{0.05}}} to get {{{100}}}.



{{{4000-2000=100*t}}} Subtract {{{2000}}} from both sides.



{{{2000=100*t}}} Combine like terms.



{{{2000/100=t}}} Divide both sides by {{{100}}} to isolate 't'.



{{{20=t}}} Divide.



{{{t=20}}} Rearrange the equation.



So it will take 20 years for an investment of $2000 to grow to $4000 with interest rate of 5% (using simple interest).