Question 241518
{{{A = P*(1 + r)^5}}}
{{{P = 1000}}}
{{{A = 1400}}}
{{{1400 = 1000*(1 + r)^5}}}
{{{1.4 = (1 + r)^5}}}
Take the log base 10 of both sides
{{{log(1.4) = 5*log(1 + r)}}}
{{{.146 = 5*log(1 + r)}}}
{{{log(1 + r) = .0292}}}
{{{10^.0292 = 1 + r}}}
{{{1.07 = 1 + r}}}
{{{r = .07}}}
The interest rate has to be greater than 7%