21.24 The effect of confidence level. An October 2011 CBS News/New York Times Poll found that 78% of a random sample of 1650 American adults thought that it was probably a good idea to significantly cut taxes for small businesses in order to create jobs. Use this poll result and Table 21.1 (see last page) to give 70%, 80%, 90%, and 99% confidence intervals for the proportion of all adults who feel this way. What do your results show about the effect of changing the confidence level?