Additional Practice 1. The Pew Research Center found in a recent survey that 61% of teenage girls surveyed use Instagram, compared to 44% of the boys. The report on this survey states that the difference is statistically significant. Explain what they meant by that. 2. The Centers for Disease Control and Prevention reported from a survey of randomly selected U.S. seniors age 65 of older that 41 1 of 1012 men and 535 of 1062 women suffered from some form of arthritis. a. Are the conditions for inference satisfied? b. Do these data indicate that a higher proportion of women of age 65 and older are affected by arthritis than men in the same age group? Carry out a significance test to answer the question. 102