irma deposited $5,000 in a savings account with simple interest. four years later, the account held $6,400…

irma deposited $5,000 in a savings account with simple interest. four years later, the account held $6,400. what was the interest rate? use the formula i = prt, where i is the interest earned, p is the principal (starting amount), r is the interest rate expressed as a decimal, and t is the time in years.

irma deposited $5,000 in a savings account with simple interest. four years later, the account held $6,400. what was the interest rate? use the formula i = prt, where i is the interest earned, p is the principal (starting amount), r is the interest rate expressed as a decimal, and t is the time in years.

Answer

Explanation:

Step1: Calculate the interest amount

The interest earned $i$ is the final amount minus the principal. So $i = 6400 - 5000=1400$. The principal $p = 5000$ and time $t = 4$ years.

Step2: Rearrange the simple - interest formula to solve for $r$

The simple - interest formula is $i = prt$. Rearranging for $r$, we get $r=\frac{i}{pt}$.

Step3: Substitute the values into the formula for $r$

Substitute $i = 1400$, $p = 5000$, and $t = 4$ into $r=\frac{i}{pt}$. So $r=\frac{1400}{5000\times4}=\frac{1400}{20000}=0.07$.

Answer:

$0.07$