EXAMPLE 10 Calculating the sample proportion

In 2014, the Harvard University Institute of Politics surveyed 3058 18- to 29-year-olds and found 1223 who had a Twitter account. Calculate the sample proportion of 18- to 29-year-olds who had a Twitter account.⁶

Solution

The survey sample size is , and the number of successes is . We calculate

Thus, the sample proportion of 18- to 29-year-olds who had a Twitter account is 0.4. That is, , or 40%, of 18- to 29-year-olds had a Twitter account.