Statistics Questions

Statistics Questions

Name:

Institution:

Statistics Questions

Question 1

n=100 students

Mean amount of money spent = $142

Standard deviation σ²= $ 47.50

90 % confidence interval can be calculated as follows;

X= 47.5 + or – (1.65) (4.75) (Gravetter & Wallnau, 2008; Privitera 2012).

= + or – 7.81

The true proportion lies between

134 to $149

95 percent confidence interval:

μ= X=/- Z(s//n)

x= 47.5+/- (1.96) (4.75)

=47.5+/-9.31

=38.19 and 56.81

Between $132 to $151

99 percent confidence interval;

X=47.5+/- (2.54) (4.75)

=47.5+ or – 12.065

=35.435 and 59.565

Between $ 129 to $154

Question 2

Sample size = 75 dishes

60 were delivered within a minute

75-60= 15 dishes took over a minute

90 percent confidence interval (Gravetter & Wallnau, 2013; Angelsen, 2011)

Observed proportion = 6/8*100=80 percent

= = or – 7.6 percent

We can be 90 percent certain that the true proportion of dishes served less than 1 minute range between 72.4 percent and 87.6 percent

95 confidence:

80 percent + or – 9.05 percent

We can be 95 percent certain that the true proportion lies between 70.95 percent and 89.05 percent

99 percent confidence:

=80 percent + or – 11.9 percent

We can be 99 percent certain that the true proportion lies between 68.1 percent and 91.9 percent

Reference

Angelsen, A. (2011). Measuring livelihoods and environmental dependence: Methods for research and fieldwork. London: Earthscan.

Gravetter, F. J., & Wallnau, L. B. (2008). Essentials of statistics for the behavioral sciences. Belmont, CA: Thomson/Wadsworth.

Gravetter, F. J., & Wallnau, L. B. (2013). Statistics for the behavioral sciences. Belmont, CA: Wadsworth Cengage Learning.

Privitera, G. J. (2012). Statistics for the behavioral sciences. Thousand Oaks: SAGE.