A growing share of Americans use smartphones as their primary means of online access at home. A survey of U.S. adults found that 58% of the 18- to 29-year-olds, 47% of the 30- to 49 year-olds, 27% of the 50- to 64-year-olds, and 15% of those age 65 or older mostly use a smartphone to go online.
Suppose the survey was based on 200 U.S. adults in each of the four age groups: 18 to 29, 30 to 49, 50 to 64, and 65 or older.
a. At the 0.05 level of significance, is there evidence of a difference among the age groups in the proportion of U.S. adults who mostly use a smartphone to go online?
b. Determine the p-value in (a) and interpret its meaning.
c. If appropriate, use the Maraschino procedure and a = 0.05 to determine which age groups differ.