C(x) = 576,000 + 160x + 0.001x2 dollars to manufacture x units of a device in an hour at one of their manufacturing centers. How many devices should be manufactured each hour to minimize average cost?'

Which of the following statements about revision is most accurate? (a) you must compose first drafts quickly (sprint writing) and return later for editing. (b) careful writers always revise as they write. (c) revision is required for only long and complex business documents. (d) some business writers prefer to compose first drafts quickly and revise later; others prefer to revise as they go.