Answer:
The interest is $1242.734 and the amount is $13242.734.
Explanation:
STEP 1: Convert interest rate of 1.5% per month into rate per year.
STEP 2: Convert 210 days into years.
STEP 3: Find an interest by using the formula , where I is interest, P is total principal, i is rate of interest per year, and t is total time in years.
In this example P = $12000, i = 18% and t = 0.57534 years, so
STEP 4: Find an amount by using the formula .
Since P = $12000 and I = $1242.734 we have