(21.26) A study of the use of social media asked a sample of 488 American adults under the age of 40 and a sample of 421 American adults aged 40 or over about their use of social media. The two-sample statistic for the social media use study (“under 40” mean minus “40 and over” mean) is . The P-value for testing the hypotheses from the previous exercise satisfies 0.001 < P < 0.005. 0.001 < P < 0.002. 0.0005 < P < 0.001.