Question Help ▼ Due to the popularity of instant messaging and social networking, informal elements such as emoticons (e.g., the symbol ":)" to represent a smile) and abbreviations (e.g., "LOL" for "laughing out loud") have worked their way into teenagers' school writing assignments. A survey interviewed 800 randomly selected teenagers by telephone on their writing habits. Overall, 421 of the teenagers admitted using at least one informal element in school writing assignments. Based on the survey results, construct a 99% confidence interval for the proportion of all teenagers who have used at least one informal element in school writing assignments. Give a practical interpretation of the interval.

An anagram of a word is just a rearrangement of its letters. How many different anagrams of "questionably" are there? Preview

The scores of a test for an engineering class of 30 students are shown here. (Due to the nature of this problem, do not use rounded intermediate values in your calculations-including answers submitted in WebAssign.) Scores: 81, 54, 55, 56, 96, 86, 98, 61, 90, 52, 92, 76, 66, 84, 79, 70, 71, 88, 62, 74, 53, 65, 55, 78, 79, 58, 60, 72, 51,80 (a) Determine the frequency (f), midpoint (x), and xf for each range and fill in the table below. (First, organize the scores into the following ranges: 50-59, 60-69, 70-79, 80-89, and 90-99.) (b) Using the following equation, determine the mean value (x) and fill in the table below. Σ(XA) n X = (c) Calculate (x − x) for each range and fill in the table below. (d) Calculate (x - x)²f for each range and fill in the table below. Range Frequency f Midpoint x 50-59 60-69 70-79 80-89 90-99 S = Enter a number. S = (e) Using the following equation, compute the standard deviation of the class scores. Σ(x-x) ²f n - 1 Σ(x-x) ²4 n - 1 = xf 29 X X - X (x - x)²f

Note: This is for practice only, this will not affect my grade.