Detailed Answer
(b) The requirement is to calculate the net benefit of
using the lockbox system. Answer (b) is correct because the net
benefit is equal to $60,875, which is equal to the interest savings
of $120,000 ($20,000 average payment × 50 payments × 2 days ×
6%) minus the cost of the service of $59,125 [$50,000 + (50
payments per day × 365 days × $0.50)].