Final answer:
Matty Kaminsky's principal balance at the beginning of June, based on a monthly interest of $400 and an annual rate of 8.5%, is approximately $56,497.18, calculated using the simple interest formula and accounting for the conversion to a monthly rate.
Step-by-step explanation:
The student's question involves calculating the principal balance of Matty Kaminsky's loan based on the provided monthly interest and annual interest rate using a 360-day year. To find the principal balance at the beginning of June, we use the formula for simple interest: Interest = Principal × rate × time. Given that the monthly interest is $400 and the rate is 8.5% (0.085) per year, we divide the rate by 12 to get the monthly rate and then rearrange the formula to solve for Principal. We find that Principal = Interest / (monthly rate × time). The time is expressed in years, so for a one-month period, we use 1/12.
Therefore, the principal balance that Matty has at the beginning of June is:
Principal = $400 / (0.085/12 × 1/12)
Principal = $400 / (0.00708…)
Principal = approximately $56,497.18
This illustration demonstrates the use of simple interest formulas to determine principal amounts and how they relate to monthly payments and interest rates.