SOCIAL SCIENCES Email on Cell Phones Although 91% of American adults own a cell phone, n...

SOCIAL SCIENCES Email on Cell Phones Although 91% of American adults own a cell phone, not all use it to check their email, many preferring to use computers instead. The percentages of cell phone owners who use their phones for email in recent years are shown in the following graph.

a. Number the years (bars) with x-values 1–4 so that x stands for years since 2009, and use linear regression to fit a line to the data. State the regression formula. [Hint: See Example 9.]

b. Interpret the slope of the line.

c. Use the regression formula to predict the percentage of Americans who will use their cell phones for email in 2020.

Source: Pew Internet

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