The correct unit price is $1.12 per pair. The error comes from dividing $67.20 by only 5 pairs (instead of 60 pairs).
Step-by-step explanation:
The contractor should have calculated the unit price as $67.20 divided by 60 pairs. Five dozen pairs is 5x12=60. This results in $67.20/60=$1.12 per pair. The error comes from dividing $67.20 by only 5 pairs (instead of 60 pairs).
