Final answer:
The APR for purchasing a living room set with add-on interest of 11% for 3 years is 33%.
Step-by-step explanation:
To find the annual percentage rate (APR) for a purchase with add-on interest, you need to calculate the simple interest rate and then convert it to an APR. The simple interest rate is given as 11% and the purchase amount is $3,800. Multiply the purchase amount by the simple interest rate to find the total interest over 3 years: $3,800 * 0.11 = $418. Next, divide the total interest by the purchase amount to find the add-on interest rate: $418 / $3,800 = 0.11. Convert this add-on interest rate to an APR by multiplying it by the number of periods in a year, in this case, 3: 0.11 * 3 = 0.33, or 33%. Therefore, the APR for purchasing the living room set is 33%.