Question 1092114
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Let x be her principal. Then her account grows each year according the formula

A = x*(1+0.05)^t = x*1.05^t:

t, year   Account

1         1.05x
2         1.05^2*x = 1.1025*x
3         1.05^3*x = 1.1576*x
4         1.05^4*x = 1.2155*x


So, if she wants to earn $2000 as simple interest in 4 years, her principle must be


1.2155x - x = 2000  ====>  (1.2155-1)*x = 2000  ====>  x = {{{2000/0.2155}}} = $9280.74   (or $9280.75 ?).
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