How can a manager forecast operating income?

It is always wise to forecast revenue by calculating a best and a worst scenario. To forecast income rapidly it would be sensible to consider projected sales revenue by the contribution margin ratio. This is the first of the possible answers listed.

Basically, forecasting income requires you to determine change in sales volume, estimate how much this might increase, convert this change in to a percentage format. Then calculate the percentage of increase or decrease you expect in sales volume.