Well, does she earn this interest per month?? or is it per year.
4% of $1000 is $40 dollars
so it would take her 2 years (If this 4% is due every year. if not just change the "year" to months) to reach 80 dollars. She just needs 20 dollars which is half of the 40 she earns per year. half of a year is 6 months so the answer would be
Sonja would need to keep her 1000 dollars in the savings account for 2 and a half years to earn 100 dollars exact.
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