Final answer:
To solve for the interest rate r in the simple interest formula I = Prt, divide the interest I by the product of the principal P and time t. Thus, the correct answer is r = I / (Pt) which corresponds to option A.
Step-by-step explanation:
To solve the formula for simple interest I = Prt for r, the interest rate, you would take the following steps:
- First, understand the formula: I = Prt which stands for Interest equals Principal times rate times time.
- To isolate r, you want to get rid of the other variables that are being multiplied with it, which are P for principal and t for time.
- Divide both sides of the equation by Pt to isolate r: I / Pt = r.
Therefore, the correct answer is A. r = I / (Pt)
Using an example from above, if you deposit $100 at a simple interest rate of 5% for one year, the simple interest would be calculated as:
$100 × 0.05 × 1 = $5
The rate r here is represented as 0.05, proving the simple interest rate calculation method.