Question 4 of 10
This test: 50 point(s) possible
This question: 5 point(s) possible
Suppose that you borrow $\$ 1000.00$ from a friend and promise to pay back $\$ 1645.00$ in 3 years. What simple interest rate will you pay?

The simple interest rate is $\square \%$ (Round to the nearest tenth as needed.)

Step 1 ：Given that the principal amount (P) is \$1000, the total amount to be paid back is \$1645, and the time (T) is 3 years.

Step 2 ：We can find the interest (I) by subtracting the principal from the total amount to be paid back, which is \$1645 - \$1000 = \$645.

Step 3 ：The formula for simple interest is \(I = PRT\), where I is the interest, P is the principal amount, R is the rate of interest, and T is the time.

Step 4 ：We can rearrange the formula to solve for R: \(R = \frac{I}{PT}\).

Step 5 ：Substituting the given values into the formula, we get \(R = \frac{645}{1000 \times 3} = 0.215\).

Step 6 ：To convert this to a percentage, we multiply by 100, which gives us \(0.215 \times 100 = 21.5\%\).

Step 7 ：Final Answer: The simple interest rate is \(\boxed{21.5\%}\).