A marketing researcher for a phone company surveys 130 people and finds that the proportion of customers who are likely to switch providers when their contract expires is 12%. Complete parts a) and b) below. a) What is the standard deviation of the sampling distribution of the proportion? SD (ModifyingAbove p with caret )equals nothing (Round to four decimal places as needed.) b) If she wants to reduce the standard deviation by half, how large a sample would she need? nequals nothing (Type a whole number.)