Final answer:
Coral invested $500 in an account with a 5.5% simple interest rate. Using the formula I = Prt, we calculated that it would take 8 years to reach $720, with a total interest of $220 needed. However, this does not match any of the options provided, indicating a possible mistake in the question or the answer options.
Step-by-step explanation:
Coral invested $500 in an account that earns simple interest at the rate of 5.5% each year. To find out how many years it will take for Coral to have $720 in her account, we can use the formula for simple interest: I = Prt, where I is the interest, P is the principal amount, r is the rate of interest per year, and t is the time in years.
First, we determine the total interest that Coral needs to earn to reach $720:
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- Total future money desired: $720
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- Principal amount (P): $500
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- Total interest needed: $720 - $500 = $220
We then apply the formula for simple interest to find the number of years (t):
I = Prt
$220 = $500 × 0.055 × t
t = $220 / ($500 × 0.055)
t = $220 / $27.50
t = 8
Therefore, it will take Coral 8 years to have $720 in her account. However, this is not one of the options given, which suggests that there might be a mistake in the options or in the calculation. To reassess as per the options provided: If Coral invested the $500 at 5.5% simple interest, the interest she earns each year is $500 × 0.055 = $27.50. By dividing the total interest needed ($220) by the annual interest ($27.50), we find: $220 / $27.50 = 8, which should be the correct number of years, though it does not match any provided option.