In 2010, PopCap Games commissioned a survey of adult mobile phone gamers in the United States and in the United Kingdom. A similar survey was also carried out in 2009. Some of the information from the survey is given below: Do you play mobile phone games for less 464 of the gamers surveyed in 2010 had than 60 minutes per week? recommended games to others. This group 2009: Yes (521) Total was asked what influenced them to (659) recommend a game. They could choose as 2010: Yes (554) Total (814) many answers as they wished. The answers, with the percentages, selecting them were: How often do you typically play on your 33% From a trusted brand mobile phone? 38% Controls simple to use 2009 2010 49% Easy to learn Daily 86 284 86% Fun to play 2-3 times per week 119 296 40% Good value once a week 59 108 36% Great graphics and sound 2-3 times a month 72 83 45% Is challenging once a month or less 323 43 41% Lots of levels/modes Total 659 814 (a) State the sampling situation (a, b or c) for calculating the standard error of the difference in the following scenarios: (i) estimating the difference between the proportion of gamers that played less than 60 minutes per week in 2010 and the proportion of gamers that played once a month or less in 2010. (ii) estimating the difference between the proportion of gamers that played daily in 2009 and the proportion of gamers that played daily in 2010. (iii) estimating the difference between the proportion of gamers that played daily in 2010 and the proportion of gamers that had recommended games to others in 2010 [3 Marke] (b) For gamers who recommended games to others in 2010, calculate a 95% confidence interval for the difference between the proportion of gamers who would recommend a game because it is fun to play and the proportion of gamers who would recommend a game because it is challenging. Interpret your results. [6 Marks] Note: You must clearly show that you have followed the "step-by-step guide to producing a confidence interval by hand" given in the Lecture Workbook, Chapter 6. Use the t-procedures tool to find values for t-multipliers and standard errors