Do you like Starbucks?

MR. ChenPeriod #3 2012-2013

By: Erick OjedaEduardo RangelMiguel Organista

Mustafa Sann

California Standards•8.0 Student organized and describe distribution of

data by using of different methods, including frequency table, histogram, standard line and bar graphs, stem-and-leaf displays, scatter plots, and box of whisker plots.

•17.0 Students determine confidence interval 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 Student determine the P-value for a statistic for a simple random sample from a normal distribution

HypothesisWe believe that the average

amount of students, juniors and seniors, who like Starbucks is less

than 64%.

Data collection We will collect data by

using stratified sample method. We ask juniors and seniors at Century whether or not they like Starbucks, to survey 100 students (50 juniors and seniors.)

Data Number of Seniors who answered Yes.

35 Number of Seniors who answered No.

15 .Number of Juniors who answered Yes.

29 .Number of juniors who answered NO

21

Statistics

From our Survey we asked Fifty Seniors and Fifty Juniors, Mean is .54592 standard deviation is .73408.

Confidence interval 95% confidential interval 1z-interval (. 54592, .73408) We are 95% confident the mean of

students that like starbucks are between .546 to .734

Hypothesis Testing Hypothesis

Test Statistics

At 5% level of significance, we failed to reject . There is not enough evidence to support the claim.

)(64.:64.:0claimH

H

a

05.05000.01

valueppropZtest

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Error Analysis Our sample proportion is 54.6%, and

the 95% confidence level for the population proportion is between 49.6% to 59.6%.

Our sample error is due to possible underrepresentation of the of the population. We might need to take more samples due to false responses, people unwilling to answer our question, and student absences.

Conclusion We hypothesized that the amount of Century

students who prefer Starbucks is less than 64%. In our survey of 100 students, (50 juniors and 50 seniors), we found the sample proportion of .54592 with the standard deviation of .73408. We conclude that the population proportion for all the students is between 49.6% and 59.6% with 95% confidence. We tested our initial hypothesis with 5% level of significance, and confirm out hypothesis is incorrect.