Simple Interest

Mr. Murphy invested his inheritance for 5 years at 3.6% simple interest. How much was the inheritance if he earned $4500 in interest?



Answer :

To determine the amount of Mr. Murphy's inheritance given that he earned [tex]$4500 in interest over 5 years at an interest rate of 3.6%, we can use the simple interest formula: \[ I = P \times R \times T \] Where: - \( I \) is the interest earned, - \( P \) is the principal amount (the initial amount of inheritance), - \( R \) is the annual interest rate (expressed as a decimal), - \( T \) is the time period the money is invested for (in years). Given: - \( I = \$[/tex]4500 \),
- [tex]\( R = 3.6\% = 0.036 \)[/tex] (converted to decimal form),
- [tex]\( T = 5 \)[/tex] years.

We need to solve for [tex]\( P \)[/tex] (the principal). Rearrange the formula to solve for [tex]\( P \)[/tex]:

[tex]\[ P = \frac{I}{R \times T} \][/tex]

Substitute the given values into the formula:

[tex]\[ P = \frac{4500}{0.036 \times 5} \][/tex]

Calculate the denominator first:

[tex]\[ 0.036 \times 5 = 0.18 \][/tex]

Now, divide the interest earned by this result:

[tex]\[ P = \frac{4500}{0.18} \][/tex]

Perform the division:

[tex]\[ P = 25000 \][/tex]

Therefore, Mr. Murphy's inheritance was \$25,000.