Question

Difficulty: MediumSimple Interest Applications

Determine the missing principal amount based on the given simple interest details. Fill in the blank with the correct numeric value.

Answer:A homeowner paid $210\$210 in simple interest on a short-term loan that lasted 1414 months. If the loan had a 4%4\% annual simple interest rate, the original principal amount borrowed was \$【4500】.

Answer

The original principal amount borrowed was $4,500\$4,500.
The correct principal is found by rearranging the simple interest formula to P=IR×TP = \frac{I}{R \times T}. By converting the 1414 months into 76\frac{7}{6} years and using the decimal rate of 0.040.04, dividing the $210\$210 interest by their product yields the original principal of $4,500\$4,500.

Step-by-Step Solution

1
Identify the known values: Interest (II), annual Rate (RR), and Time (TT) in months.
I=210I = 210, R=0.04R = 0.04, and T=14T = 14 months
These are the given variables needed to set up the simple interest equation.
2
Convert the loan duration from months into years.
T=1412=76T = \frac{14}{12} = \frac{7}{6} years
The simple interest formula requires time to be in years when the given interest rate is annual.
3
Substitute the values into the simple interest formula (I=PRTI = PRT) to isolate Principal (PP).
210=P×0.04×76210 = P \times 0.04 \times \frac{7}{6}
This establishes the equation with only one unknown variable.
4
Calculate the product of the rate and time, then divide the total interest by this product.
P=2100.286=210×60.28=12600.28=4500P = \frac{210}{\frac{0.28}{6}} = 210 \times \frac{6}{0.28} = \frac{1260}{0.28} = 4500
Simplifying the expression yields the exact borrowed amount.

Key Concept

Solving for the principal using the simple interest formula I=PRTI = PRT by converting time in months to a fraction of a year.
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