Question

Clara invests $5,000 in an account that pays 6.25% interest per year. After how many years will her investment be worth $10,000?

Answer 1

I think the interest is compounded yearly, if so
A = $10000
P = $5000
r = 6.25% = 0.0625
A = P (1+r/100)^t where t denotes time in years
10000 = 5000 (1+0.0625)^t
10000/5000 = 1.0625^t
2 = 1.0625^t
Use logarithms or a scientific calculator
t = 11.5
In 11.5 years $5000 investment be worth of $10000
>>>>>>>>>>>>>
In case the interest is simple interest
Interest = Amount - Principal = $10000-$5000 = $5000
Time = 100*Interest / (Principal*Rate
= 100*5000 / (5000*6.25)
= 16 years
In 16 years $5000 investment be worth of $10000

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