Question

Find the simple interest rate if $1,200 earns $81 interest in 9 months.

Answer 1

Answer: the simple interest rate is 9%

Step-by-step explanation:

The formula for determining simple interest is expressed as

I = PRT/100

Where

I represents interest paid on the amount invested.

P represents the principal or amount invested.

R represents interest rate

T represents the duration of the investment in years.

From the information given,

P = $1200

T = 9 months = 9/12 = 0.75 year

I = $81

Therefore,

81 = (1200 × R × 0.75)/100

81 = 900R/100 = 9R

R = 81/9

R = 9%

Answer 2

1) Plug the numbers into the equation for a simple interest rate. The equation is I = Prt, where P is the initial amount, r is the interest rate, and t is the time in years. 2) You have to turn the time into years, so put it over 12 (the months in a year) to turn it into a fraction for the unit of years, and plug in the equation to get I = 1200*0.81*(9/12). 3) Multiply this equation out to get 729.00, this is the answer. Answer: $729.00 interest. **TAKE THIS WITH A GRAIN OF SALT, you wrote the interest as dollars, but in this equation I assumed you meant to write it was a percent. If you did make a mistake and the 81 interest is a percent, then the math in this equation is correct. If it is an amount of money, then don’t copy it because it would be incorrect.