When he was 18,Gerald put $100 into an account at an interest rate of 8 percent.He now has about $171.38 in this account.How many years did Gerald leave this money in his account?
A)5 years
B)6 years
C)7 years
D)8 years

Question

Quizplus · Accepted Answer

We can use the formula A=P(1+r/n)^nt, where A is the final amount, P is the initial amount, r is the interest rate as a decimal, n is the number of times interest is compounded per year, t is the time in years. Plugging in the given values, we get:
171.38 = 100(1+0.08/1)^(1*t)
Taking the natural logarithm of both sides and solving for t, we get:
t = ln(171.38/100)/ln(1.08) = 7.06
Since we cannot have a fraction of a year, we round down to the nearest whole number, which is 7. Therefore, Gerald left the money in the account for 7 years.

When He Was 18,Gerald Put $100 into an Account at an Interest