Newark Broadcasting Company (NBC), trying to decide on their own strategy, conducted a poll in major metropolitan areas and found that 39 households were likely to purchase an HDTV within the next 18 months, while the remaining 161 were not likely to purchase an HDTV within the next 18 months.

How large would the sample have to be in order for the margin of error to be no more than 3%?Assume that the sample proportion calculated calculated from the above data is the population proportion (assume alpha=0.05).