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 CaSQ 1A - Mean of Belly Button Heights
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How to: Get a Random Sample from CensusAtSchool
Go to the CensusAtSchool Random Sampler and get a sample.
Reference year: Select year Sample size: at least 30 students
Select questions: Belly button height
Location: Select location Year level: Select year level
To protect privacy there is a rule built into the sampler that the requested sample size cannot exceed 10% of the respondents for the parameters entered.
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Task:
1. In your CensusAtSchool random sample, find the question about belly button height.
Outliers can be the result of an error or an unusual value. All outliers need to be investigated to see whether they are errors or true outliers. If they are errors, we remove them. We can often identify possible outliers by eye as they are different to the rest of the data set. In this case, we will consider numbers outside the range of 80 – 110cm to be outliers.
Write ten values for belly button heights below. If you find an outlier or a blank, go to the next value in your list.
2. Showing your working, calculate the mean.
Mean belly button height of my random sample is: _______________
3. You are told that the mean belly button height of a sample is 103 cm. Create a realistic sample of ten belly button heights below that will give you a mean of 103cm. You cannot have more than two numbers that are identical.
4. Get your neighbour to check your data sample of ten has a mean of 103cm.
“This data sample of ten has a mean of 103cm.” signed: __________________________
Extension:
5. Explain in words how you went about creating a sample of ten numbers that had a mean of 103cm.
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To provide any feedback regarding this activity, please contact ABS Education Services on 1800 623 273 or email education@abs.gov.au.
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This page last updated 11 February 2013 | 
