The adjusted budget was created by multiplying each item in the budget by the ratio 105/100; in other words, each item was adjusted upward by 5%. This procedure provides valid benchmarks for revenues and for costs that are strictly variable, but overstates what fixed and mixed costs should be. Fixed costs, for example, should not increase at all if the activity level increases by 5%—providing, of course, that this level of activity is within the relevant range. Mixed costs should increase less than 5%.
To evaluate how well revenues and costs were controlled, it is necessary to estimate what the revenues and costs should have been for the actual level of activity using a flexible budget that explicitly recognizes fixed and mixed costs. The flexible budget amounts can then be compared to the actual results to evaluate how well revenues and costs were controlled.