Question

Shane deposited $200 into an account and earned $36 in interest after 3 years. Use the formula I = prt, where I represents simple interest, p represents principal, r represents interest rate, and t represents time in years. What is the interest rate?

Answer 1

Answer:20%

Step-by-step explanation:

Let r represent rate of interest.

We have been given that Mika invested $200 into a certificate of deposit. After 6 months, the balance was $220.

We will use simple interest formula to solve our given problem.

I = Amount of interest,

P = Principal amount,

r = Rate of interest in decimal form,

t = Time in years.

First of all, we will find amount of interest by subtracting $200 from $220 as:

6 month = 1/2 year = 0.5 year

Upon substituting our given values in simple interest formula, we will get:

Upon dividing both sides by $100, we will get:

Since interest rate is given in decimal, so we will multiply 0.2 by 100 to convert our answer in percentage.

Therefore, the interest rate on the deposit was 20% and option B is the correct choice.

Answer 2

The interest rate = 6 %

Step-by-step explanation:

We have I = prt, where I represents simple interest, p represents principal, r represents interest rate, and t represents time in years.

Here principal, p = 200 $

Number of years , t = 3

Interest received, I = 36$

We need to find rate of interest.

Substituting

36 = 200 x r x 3

r =
`(36)/(200*3)`= 0.06 = 6%

The interest rate = 6 %