Question

Difficulty: MediumSimple Interest

A hospital administrator places $12,000\$12,000 into a fixed-term savings certificate that earns an annual simple interest rate of 4.2%4.2\%. If no other deposits or withdrawals are made, what is the total accumulated balance, in dollars, of the certificate after exactly 30 months?

Answer: 13260

Answer

The total accumulated balance is 13260.
The correct answer is found by first converting the 30-month time period into 2.5 years (30÷12=2.530 \div 12 = 2.5), and the 4.2%4.2\% interest rate into the decimal 0.0420.042 (4.2÷100=0.0424.2 \div 100 = 0.042). Using the simple interest formula I=P×R×TI = P \times R \times T, the interest earned is $12,000×0.042×2.5=$1,260\$12,000 \times 0.042 \times 2.5 = \$1,260. Adding this interest to the original principal of $12,000\$12,000 gives a total accumulated balance of $13,260\$13,260.

Step-by-Step Solution

1
Convert the interest rate to a decimal and the time period to years.
R=4.2%=0.042R = 4.2\% = 0.042, and T=30 months÷12 months/year=2.5 yearsT = 30 \text{ months} \div 12 \text{ months/year} = 2.5 \text{ years}.
The standard simple interest formula requires the interest rate as a decimal and the time expressed in years.
2
Calculate the total interest earned using the simple interest formula I=P×R×TI = P \times R \times T.
I=12000×0.042×2.5=1260I = 12000 \times 0.042 \times 2.5 = 1260
This determines how much additional money the certificate earns over the 30-month period.
3
Calculate the total accumulated balance by adding the interest earned to the original principal.
Total Balance = 12000+1260=1326012000 + 1260 = 13260
The question asks for the total accumulated balance, which includes both the initial deposit (principal) and the earned interest.

Key Concept

Calculating simple interest over a fractional year and determining the total accumulated amount.
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