Smartphones: A study found that of 4900 cell phone owners in 2011 , 585 owned a smartphone. The study was repeated in 2013 , and 975 out of 4900 cell phone owners owned smartphones. Part: 0 / 2 Part 1 of 2 (a) Construct a 90% confidence interval for the increase in the proportion of cell phone owners with smartphones between 2011 and 2013 . Use the TI-84 Plus calculator and round the answers to three decimal places. A 90 % confidence interval for the increase in the proportion of cell phone owners with smartphones between 2011 and 2013 is 1