Gabriela Gonzalez

Alyssa Vasquez

Elizabeth Carlos

Columba Nava

Period 5

2011-2012

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.

Hypothesis

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

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.

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.

Histogram

135.4 256.25 377.1 497.9 618.75 739.6 860.40

4

8

12

Prom Cost

Amount Spent

Nu

mb

er

of

Sen

iors

Statistics

Find sample mean and standard deviation.

STAT TEST Z-Interval

Sample Mean:

Standard Deviation:

x 58.266

08.163

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)

Hypothesis Testing

275: H )(claim

275: Ha

05.0744. P

Hypothesis:

Statistics:

Conclusion:

At 5% level of significance, we failed to reject. There is enough evidence to support our claim.

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.

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.