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 than 60 minutes per week? 2009: Yes (521) Total (659) 2010: Yes (554) Total (814) How often do you typically play on your mobile phone? Daily 2-3 times per week once a week 2-3 times a month once a month or less Total 2009 86 119 59 72 323 659 2010 284 296 108 83 43 814 464 of the gamers surveyed in 2010 had recommended games to others. This group was asked what influenced them to recommend a game. They could choose as many answers as they wished. The answers, with the percentages, selecting them were: 33% From a trusted brand 38% Controls simple to use 49% Easy to learn 86% Fun to play 40% Good value 36% Great graphics and sound 45% Is challenging 41% Lots of levels/modes (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 for less than 60 minutes per week in 2009 and the proportion of gamers that played for less than 60 minutes per week in 2010. (ii) (iii) estimating the difference between the proportion of gamers that played for at least 60 minutes per week in 2010 and the proportion of gamers that played daily in 2010. for gamers who recommend games to others, estimating the difference between the proportion of all gamers who, in 2010, would have recommended a game that is fun to play and the proportion of all gamers who, in 2010, would have recommended a game that is easy to learn.