The formula for simple interest is given by:

$I = P \times r \times t$

Where:

• $I$ is the interest earned,
• $P$ is the principal (initial investment),
• $r$ is the annual interest rate (as a decimal),
• $t$ is the time in years.

Given:

• $P = 800$ dollars,
• $r = 5\% = 0.05$,
• $t = 3$ years.

Now, substitute the values into the formula:

$I = 800 \times 0.05 \times 3$ $I = 800 \times 0.15 = 120$

Rohan will earn $120 in interest over 3 years.

Would you like further details or have any questions?

Here are 5 related questions for practice:

1. How much total amount will Rohan have after 3 years?
2. What would the interest be if the rate was 6% instead of 5%?
3. How much interest would be earned if the investment period was 5 years?
4. What would happen to the interest if the principal was doubled?
5. How does compound interest differ from simple interest?

Tip: Always convert percentages to decimals before using them in interest calculations by dividing by 100.