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Use the formula for simple interest I = P*r*t.
Adopt it to your case
150 = 600*0.05*t,
where "t" is the time in years.
From this equation, obtain the answer t = = 5 years.
Solved.
There is another way to solve it without using equations.
At 5% annual interest, the principal of 600 units produces 600*0.05 = 6*5 = 30 units of interest each year.
Hence, the interest of 150 units will be produced in 150/30 = 5 years.
giving you the same answer.
Solved twice, by two different methods, for your better understanding.
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To see many other similar (and different) solved problems on simple interest accounts, look into the lesson
- Simple interest percentage problems
in this site.
Learn the subject from there.