190 % of simple interest rate does she need to achieve the necessary amount of principal.
we know that
The simple interest formula is equal to
A=P(1+rt)
where
A = Final Investment amount
P = Principal amount of money
r = rate of interest
t = Number of Time Periods
in this problem we have
t= 25 years
P= $80,000
A= $4,000,000
r=?
substitute in the formula above
4,000,000 = 80,000(1+25r)
50 = 1+25r
50-1=25r
49=25r
r=1.96
Convert to percentage
r = 1.9 * 100
= 190 %
The simple interest rate is 190%
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