When understanding the true order size savings of finding the correct amount for an ordering cost, the true order size savings is not just the ratio between the original and the new cost. It is actually the square root of the two costs put into ratio form.
In other words, take the square root of the old ordering costs:
SQRT($82)=9.0554
And the new, correct, ordering costs:
SQRT($42)=6.4807
Find the ratio between the square root of the two ordering costs:
9.0554/6.4807=1.3972
This ratio is the ratio can be used to find the relation between the old EOQ and the new EOQ without having to use the EOQ formula. This can be used to know the % change of the new EOQ, as well.
The two EOQ are not related in this way:
$82/$42 = 1.952
