Final answer:
Interest for the provided notes was calculated using the simple interest formula, which is the product of the principal, rate, and time. The time is expressed as a fraction of a year to ensure accuracy for non-annual periods.
Step-by-step explanation:
The student asked to determine the interest on several notes with different principals, rates, and time periods. Here are the calculations:
- (a) $2,000 at 6% for 90 days = $2,000 × 0.06 × ⅓ = $30.00
- (b) $900 at 9% for 5 months = $900 × 0.09 × ⅔ = $33.75
- (c) $3,000 at 8% for 60 days = $3,000 × 0.08 × ⅕ = $40.00
- (d) $1,600 at 7% for 6 months = $1,600 × 0.07 × 0.5 = $56.00
To obtain these values, simple interest was calculated by multiplying the principal by the rate and the portion of the year the money is borrowed or invested. It's important to convert the time periods into fractions of a year (for example, 90 days is ⅓ of a year, and 5 months is ⅔ of a year) to correctly calculate the interest for such periods.