Transcript How many hours do you spend on Facebook a day?

Adriana Alejandre
Diana Ruvalcaba
Rosa Castro
Period 2
2011-2012
California Standards
8.0 Students organize and describe distributions of data by using a
number of different methods , including frequency tables,
histogram, standard line and bar graphs, stem-and leaf displays,
scatter plots, and box-and-whisker plots.
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.
• We believe that the population mean of how many
hours do you spend on Facebook a day is 5 hours.
Data Collection
 We collected data by using the cluster method by asking
seniors in our lunch period and throughout the day. We
each asked 14 seniors to get the total survey of 42
seniors.
Data
 Length of commute (in hours)
 3, 2, 3, 6, 4, 1, 5, 2, 3, 4, 2, 2, 7, 3, 1, 8, 3, 1, 4,
2, 2, 3, 3, 2, 1, 2, 2, 3, 4, 3, 3, 4, 2, 5, 5, 4, 3, 2,
1, 2, 1, 3
Histogram
Hours spent on Facebook
20
18
16
Number of students
14
12
10
8
6
4
2
0
1.58
2.745
3.915
5.08
6.245
Time (in hours)
7.415
8.58
9.73
Statistics
 From our survey, student’s sample mean time is 3
hours with a sample standard deviation of 1.592
hours.
Confidence Interval
 95% Confident Interval
 Z-Interval
 (2.518,3.481)
 We are 95% confident that the population
mean of How many hours do you spend on
Facebook a day is between 2.51 to 3.48 hours.
Hypothesis Testing
 Claim: We believe that the population mean of how
many hours do you spend on Facebook a day is 5 hours.
H 0 :   5(claim)
Ha :   5
P  value: 3.942059E 16    .05
 At 5% level of significance we reject the Ho. There is not
enough evidence to support our claim (Hypothesis).
Error Analysis
 Our sample mean is 2.5 to 3.4 hours. And the 95%
confidence level for the population mean is between
2.518 to 3.481 hours. The marginal error is about 3
hours.
 Our sample error is due to possible
underrepresentation of the population. We might
need to take more samples due to only asking seniors
about how many hours they spend on Facebook a day.
Conclusion
 We are 95% confident that the
population mean of “How many hours do
you spend on Facebook a day”, is between
(2.518 to 3.481) hours. We test our
initial hypothesis with 5% level of
significance , and we confirm our
hypothesis was incorrect.