Question

Statistics Part 2 Exercises 1. A random sample of 755 U.S. cell phone users age 18 and older found that the average number of text messages sent or received per day is 41.5 messages with margin of error 12.2 messages. a) Give the population. b) Give the sample. c) What value is the best estimate of the actual average number of text messages sent received by all U.S. cell phone users age 18 and above? d) Find the confidence interval. What does it mean? e) A child psychologist claims in an editorial that the average number of text messages sent or received by 12 to 17 year-olds is 63 messages. If this value is accurate, is the number of text messages sent or received by teens (12-17 year-olds) different than the number sent by adults (18+)? Explain.

Answer 1

using given information, (a) Populatisa u.s. cell phone user age 18. Sample : 755 users best estimate is sumple mean. Sample mean is unbiased estimates population menn. mean = 41.5 (d) Confidence internal. Lower limit X - marginstemos = 41.5 12.2 limit = x Tot Upper limit = + margin of cosos = 41-5 + 12.2 53.7 C 29.3, 53.7) 95% of the sampre as lies between (29.3.53.7) within this internal

e Thisralnes are diffront becuse. The te se't messages that are relieved Pungon adults age 18 is from 29.3 to 53.2 so this mesage and beyond me elpper limit of me interval ". This megunge from 12 to 17 yours