As written above, this recipe yields ~1/2 to 3/4 cup servings per person, which is appropriate for serving as an accompaniment. If serving a crowd that may have heartier appetites or as a full side dish, add 2-4 more bags slaw and a bit more ranch. Taste for seasoning and adjust the other ingredients if desired to taste.
For the ranch, go with a quality ranch (I like Bolthouse or Ken's Steakhouse ranch dressings). Bolthouse is available in 22 oz bottles; Ken's is available in 24 oz bottles.
Note that as written, this is a light and loose slaw. If you want the consistency to be more traditional, then double the amount of mayonnaise.