Transcript How Long Do You Take To Shower?

Alan Flores, Kathy Alvarado, Carol Prieto
Period: 5
2011-2012
 8.0 Students organize and describe distributions of data by using a number of
different methods, including frequency table, histograms, standards 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-valve for a statistic for a simple random sample
from a normal distribution.
 We believe that the amount to take a shower is 30
minutes.
 We will collect data by using the random sampling
method. We ask every third person we see walking
around school.
 Length of shower
 25,15,25,30,30,10,15,15,20,25,10,20,10,15,11,15,8,20,10,6,17,25
,21,20,13,9,10,10,15,8,12,25,10,5,20,6,10,10,11,19,12,13
How long do you take to shower?
45
40
35
People
30
25
20
15
10
5
0
15.357143
36.0714285
56.785714
77.5
98.2142865
Time (in Min)
118.92857
139.642855
160.357145
 Find sample mean and sample standard deviation .
Stat→ test→ 1 var stat
 Sample mean x = 15.1428
 Sample Standard deviation sx=6.6426
Find 95% confidence interval
STAT→ Test→ 7. z-interval→ Select “stats”
  6.643
___
X  15.14
n  42
C  level  0.95
Calculate:
(13.13, 17.15)
Conclusion: We are 95% confident that the population mean of how long do you
take to shower is between 13.13 and 17.15 minutes.
Claim: We believe that the amount to take a shower is 30
minutes.
Ho :   30(claim )
Ho :   30
Test Statistics (z-test)
P  value : 0    0.05
At 5% level of significance we reject the claim that there is
not enough evidence to support our claim (hypothesis)
Our sample mean is 15.1428 minutes, and the 95%
confidence level for the population mean is between
13.134 to 17.152 minutes. The marginal error is about
2.0092 minutes.
Our sample error is due to possible underrepresentation of the population. We might need to
take more samples due to people taking a shower,
people fail to check their survey by asking students.
 We are 95% confident that the population mean how
long do you take to shower is between (13.134min to
17.152min)