Final answer:
To calculate simple interest on $1,300 for 3 months at a 21/2% annual rate, convert the rate to a decimal (0.105), then use the formula Interest = Principal × rate × time to find the interest ($34.13).
Step-by-step explanation:
To find the simple interest given the principal, time, and interest rate, you can use the formula:
Interest = Principal × rate × time
In this case, the principal is $1,300, the time is 3 months (which is 3/12 or 0.25 years when converted to years since we're assuming 360 days in a year), and the rate is 21/2% or 10.5% (since 21/2 = 10.5).
First, we convert the annual rate to a decimal by dividing by 100:
10.5% / 100 = 0.105
Then we calculate the interest:
$1,300 × 0.105 × 0.25 = $34.125
Therefore, the simple interest for 3 months at a rate of 21/2% on a principal of $1,300 is $34.13 (rounded to two decimal places).