Solve for the unknown number of years in each of the following: a) Principal amount = 500, Interest rate = 8%, Simple interest = 400, b) Principal amount = 100, Interest rate = 10%, Simple interest = 550.

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Answer: For Principal amount = 500, Interest rate = 8%, Simple interest = 400, The number of years is 10, and for Principal amount = 100, Interest rate = 10%, Simple interest = 550, the number of years is 55.

Let's understand how we arrived at the solution.

Explanation:

We use the formula to calculate simple interest to solve the problems:

⇒ (Principal × Years × Interest Rate) / 100 = Simple Interest

a) In this case, after we substitute the values in the formula:

⇒ (500 × Years × 8) / 100 = 400

⇒ Therefore, Years = 10

b) In this case, after we substitute the values in the formula:

⇒ (100 × Years × 10) / 100 = 550

⇒ Therefore, Years = 55

Hence, for principal amount = 500, interest rate = 8%, simple interest = 400, The number of years is 10, and for principal amount = 100, interest rate = 10%, simple interest = 550, the number of years is 55.