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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 =
= $9280.74 (or $9280.75 ?).