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.)