Question

Difficulty: MediumSimple Interest Applications

Determine the missing interest rate and the final maturity value. Fill in the blanks with the correct numeric values.

Answer:A municipal worker invests \\ 5,000 intoafixed−ratesavingscertificate.Thecertificatepaysanannualsimpleinterestrateof【3.75】 into a fixed-rate savings certificate. The certificate pays an annual simple interest rate of 【3.75】\\%.After. After 4 years,thecertificatehasearned years, the certificate has earned \\750750 in interest, bringing the total maturity value to \\【5750】$.

Answer

The annual simple interest rate is 3.75% and the total maturity value is $5,750.
The missing interest rate is found by rearranging the formula I=PRTI = PRT to solve for rate: R=IPTR = \frac{I}{PT}. Dividing the interest ($750\$750) by the product of the principal ($5,000\$5,000) and the time (44 years) gives a decimal of 0.03750.0375, which is 3.753.75\\%. The total maturity value is simply the initial principal ($5,000\$5,000) plus the interest earned ($750\$750), which equals \\ 5,750$.

Step-by-Step Solution

1
Identify the given values for the simple interest formula.
Principal (PP) = \\ 5,000 ,Interest(, Interest ( I )=) = \\750750, Time (TT) = 44 years.
To find the missing annual interest rate, we must first list the known values for the formula I=PRTI = PRT.
2
Substitute the known values into the simple interest formula and solve for the rate (RR).
750=5000×R×4⇒750=20000×R⇒R=75020000=0.0375750 = 5000 \times R \times 4 \Rightarrow 750 = 20000 \times R \Rightarrow R = \frac{750}{20000} = 0.0375. Converting this decimal to a percentage gives 3.753.75\\%.
Isolating RR allows us to determine the annual percentage rate required to earn the specified interest.
3
Calculate the total maturity value (AA) by adding the interest earned to the original principal.
A=P+I⇒A=5000+750=5750A = P + I \Rightarrow A = 5000 + 750 = 5750.
The total balance at maturity is the sum of the initial investment and the accumulated interest.

Key Concept

Simple Interest Applications
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