Question

How long will it take a certain sum of money to triple itself at 13% per annum

simple interest?

Answer 1

15.38

steps

a.

round the percentage

use 10% or .10 = 10

keep adding 10

100

110

120

130

etc

for a rough guess

b.

Time (in years) = (Triple Amount - Original Amount) / (Original Amount * Interest Rate)

3x-x=2x

time = 2x / x * .13

time = 15.38

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