Apple Inc. posted its first quarterly revenue drop in more than a decade and forecast another decline in the current period, dragged down by waning demand for the iPhone. Shares fell as much as 5.4 percent in extended trading. Sales in the third quarter, which ends in June, will be $41 billion to $43 billion, the Cupertino, California-based company said Tuesday in a statement. On average, analysts estimated revenue of $47.4 billion, according to a Bloomberg survey. Second-quarter sales slid 13 percent and IPhone shipments fell 16 percent.