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?

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

2009

2010

Daily

86

284

2-3 times per week

119

296

once a week

59

108

2-3 times a month

72

83

once a month or less

323

43

Total

659

814

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 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 Marks]

(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.