To calculate the annual simple interest rate $r$ for Abid's investment, we can use the formula for simple interest:

$I = P \times r \times t$

where:

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

Given:

• $I = \$153.60$ (total interest earned),
• $P = \$2400$,
• $t = 4$ years.

We need to solve for $r$:

$153.60 = 2400 \times r \times 4$

$153.60 = 9600 \times r$

$r = \frac{153.60}{9600}$

$r = 0.016$

To express $r$ as a percentage:

$r = 0.016 \times 100 = 1.6\%$

The annual simple interest rate $r$ is 1.6%.

Would you like more details or have any questions?

Here are some related questions:

1. What would be the total amount in the account after 4 years including interest?
2. How would the interest amount change if the rate were 2% instead?
3. How much interest would Abid earn in 1 year at the same rate?
4. What would be the interest earned if the principal were $3000 instead?
5. How much would Abid have after 5 years at the same rate?
6. What is the formula for calculating simple interest?
7. How does the simple interest rate compare to compound interest rates?
8. What are the advantages of a simple interest account over a compound interest account?

Tip: Understanding the difference between simple and compound interest can help you make better financial decisions. Simple interest is calculated on the principal alone, while compound interest is calculated on the principal and the accumulated interest.