2. Gabriela Gonzalez Alyssa Vasquez Elizabeth Carlos Columba Nava Period 5 2011-2012

3. Standards  8.0- Students organize and describe distributions of data by using a number of different methods, including frequency tables, histograms, standard line and bar graphs, stem-and-leaf displays, scatter plots, and box-and-whisker plot.  17.0- students determine confidence intervals for a simple random sample from a normal distribution of data and determine the sample size required for a desired margin of error.  18.0- students determine the p-value for a statistic for a simple random sample from a normal distribution.

4. Hypothesis  We believe Seniors average amount spent on Prom is $275.00.

5. Data Collection  We collected data by asking every fifth senior in each class.  Cluster Sample (asked seniors only)  Systematic (asked every fifth senior)  There are four people in our group, as a group we needed to collect 40 data points. So we decided to collect 10 data points per person.

6. Data  Amount of money spent on each person going to Prom.  95, 100, 100, 75, 90, 250, 238, 300, 325, 300, 75, 100, 140, 95, 90, 238, 300, 297, 180, 260, 300, 600, 350, 300, 400, 400, 400, 350, 350, 345, 400, 200, 800, 300, 100, 500, 400, 500, 300, 350.

7. Histogram

8. Statistics  Find sample mean and standard deviation. STAT  TEST  Z-Interval Sample Mean: Standard Deviation:

9. Confidence Interval  95% confident interval  Z-Interval  ($216.04-$317.12)  We are 95% confident that the population mean of seniors spending for Prom is $216.04-$317.12)

10. Hypothesis Testing Hypothesis: Statistics: Conclusion: At 5% level of significance, we failed to reject. There is enough evidence to support our claim.

11. Error Analysis Our Sample mean is $266.58, and the 95% confidence level for the population mean is between $216.04$317.12. The marginal error is about $50.54. Our sample mean error is due to possible underrepresentation of the population. We might need to take more samples due to students absences, and giving false information.

12. Conclusion We hypothesized that the amount of money spent by Seniors on Prom was $275.00. In our survey of 40 students, we found that the sample mean was $266.58 with a standard deviation of $163.08. We conclude that the population mean for all Senior students is between $216.04-$317.12 with 95% confident. We test our initial hypothesis with 5% level of significance, and confirm our hypothesis is correct.