Alan Flores, Kathy Alvarado, Carol Prieto Period: 5

2011-2012

How Long Do You Take To Shower?

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.

California Standards

We believe that the amount to take a shower is 30 minutes.

Hypothesis

We will collect data by using the random sampling method. We ask every third person we see walking around school.

Data Collection Method

Length of shower25,15,25,30,30,10,15,15,20,25,10,20,10,15,11,

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

Data

15.357143 36.0714285 56.785714 77.5 98.2142865 118.92857 139.642855 160.3571450

5

10

15

20

25

30

35

40

45

How long do you take to shower?

Time (in Min)

People

Histogram

Find sample mean and sample standard deviation .

Stat→ test→ 1 var stat

Sample mean x = 15.1428

Sample Standard deviation sx=6.6426

Statistics

95.0

42

14.15

643.6___

levelC

n

X

Confidence IntervalFind 95% confidence intervalSTAT→ Test→ 7. z-interval→ Select “stats”

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.

Test Statistics (z-test)

At 5% level of significance we reject the claim that there is not enough evidence to support our claim (hypothesis)

Hypothesis

30: aH

__

X

30:

)(30:

Ho

claimHo

05.00: valueP

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 under-representation 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.

Error Analysis

We are 95% confident that the population mean how long do you take to shower is between (13.134min to 17.152min)

Conclusion