To calculate simple interest, we use the formula:

$I = P \times r \times t$

where:

• $I$ is the interest,
• $P$ is the principal amount ($5000),
• $r$ is the annual interest rate (5.9% or 0.059 as a decimal),
• $t$ is the time period in years.

First, convert 21 days into years: $t = \frac{21}{365} \approx 0.05753 \text{ years}$

Now, plug the values into the formula:

$I = 5000 \times 0.059 \times 0.05753$

$I \approx 17.01$

So, the simple interest earned is $17.01, rounded to the nearest cent.

Would you like more details or have any questions?

Here are 5 related questions:

1. What is the formula for compound interest and how does it differ from simple interest?
2. How would the interest change if the time period was in months instead of days?
3. What would the interest be if the rate was compounded daily?
4. How can you calculate the future value with simple interest?
5. How does changing the principal affect the amount of interest earned?

Tip: Always ensure that time periods in interest calculations are consistent with the rate's time frame (e.g., annual rates need time in years).