Final answer:
The effective monthly interest rate is higher than 0.5% due to the reducing balance of the loan. The effective annual and semi-annual rates require compounding the monthly rate, which cannot be precisely determined without further calculation.
Step-by-step explanation:
The question attempts to calculate the effective monthly and annual interest rates when financing consumer electronics through a retailer which initially quotes a simple interest calculation. Let's first articulate the effective monthly interest rate. Given that the interest on the original $1,000 is 12% over two years, the amount paid monthly is $46.67. To get the effective monthly rate, one must recognize that this payment plan implies a reducing balance loan rather than one where interest applies to the full $1,000 throughout the entire term.
To find the effective monthly rate, you would need to solve for the interest rate (i) in the installment loan formula P = (PV * i) / (1 - (1 + i)^-n), where P is the monthly payment ($46.67), PV is the present value ($1,000), n is the total number of payments (24), and i is the monthly interest rate. This requires an iterative process or financial calculator to solve. However, without calculating it precisely, we can affirm that the effective monthly rate is indeed higher than (0.5%)—the simple division of the annual nominal rate (6%) by 12 months—since the initial loan amount reduces with each payment made.
For the effective annual rate, one would typically annualize the effective monthly rate found above. This is not a simple multiplication by 12 due to the compounding effect. Instead, the formula (1 + i)^12 -1 can be used, where i is the monthly rate.
The semi-annual effective rate can be found by calculating (1 + i)^6 -1 where i is the monthly rate, to reflect compounding every half year. Calculating the exact effective rates would require further details not provided in the question, specifically the actual formula or tool to calculate the monthly instalment.