It is typically beneficial for companies to take advantage of early$-$payment discounts allowed on purchases made on credit. To see why this is the case, determine the effective rate of interest associated with not taking advantage of the early$-$payment discount for each of the following situations. Assume in each case that payment is made on the $60$th day of the billing cycle.

Required:

$1.$ What is the opportunity cost of not taking advantage of the discount associated with purchases made under the following terms: $3/20,$ n$/60?$

$2.$ What is the opportunity cost of not taking advantage of the discount associated with purchases made under the following terms: $2/20,$ n$/60?$

$3.$ To motivate managers to take early$-$payment discounts, what is the appropriate accounting treatment for purchase discounts?$($Do not round intermediate calculations. Enter your final answer as a percentage rounded to $2$ decimal places $($i$.$e$.,\mathrm{.}1524=15\mathrm{.}24\%).)$