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

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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%