brianna deposited $6,000 in a savings account with simple interest. one year later, the account held $6,420…

brianna deposited $6,000 in a savings account with simple interest. one year later, the account held $6,420. 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.

brianna deposited $6,000 in a savings account with simple interest. one year later, the account held $6,420. 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 earned

The initial deposit (principal $p$) is $6000$ and the final amount is $6420$. So the interest earned $i=6420 - 6000=420$. The time $t = 1$ year and $p = 6000$.

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

The simple - interest formula is $i=prt$. We want to find $r$, so we can rewrite the formula as $r=\frac{i}{pt}$.

Step3: Substitute the values of $i$, $p$, and $t$ into the formula for $r$

Substitute $i = 420$, $p = 6000$, and $t = 1$ into $r=\frac{i}{pt}$. We get $r=\frac{420}{6000\times1}=0.07$.

Step4: Convert $r$ from decimal to percentage

To convert a decimal to a percentage, we multiply by 100. So $r = 0.07\times100 = 7%$.

Answer:

$7$