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CanadaON
Grade 12

Limitations of measures of centre and spread

Interactive practice questions

A journalist wanted to report on road speed cameras being used as revenue raisers. She obtained data that showed the number of times $20$20 speed cameras issued a fine to motorists in one month. The results were:

$101,102,115,115,121,124,127,128,130,130,143,143,146,162,162,163,178,183,194,977$101,102,115,115,121,124,127,128,130,130,143,143,146,162,162,163,178,183,194,977

a

Determine the mean number of times a speed camera issued a fine in that month. Give your answer correct to one decimal place.

b

Determine the median number of times a speed camera issued a fine in that month. Give your answer correct to one decimal place.

c

Which measure is most representative of the number of fines issued by each speed camera in one month?

the mean

A

the median

B
d

Which score causes the mean to be much greater than the median?

e

The journalist wants to give the impression that speed cameras are just being used to raise revenue. Which statement should she make?

A sample of $20$20 speed cameras found that the median number of fines in one month was $136.5$136.5.

A

A sample of $20$20 speed cameras found that, on average, $182.2$182.2 fines were issued in one month.

B
Easy
5min

Teachers at a school suspected that the participation rate of students aged 13 to 15 in extra curricular activities was low compared to other ages. They asked a sample of students if they had participated in any activities in the last year, and recorded their ages. The results are presented in the dot plot.

Easy
4min

In a countrywide census, information is gathered to determine the make up of the population.

Easy
< 1min

In a study of home affordability, a sample of $10$10 families were asked what percentage of their household income goes towards mortgage repayments (to the nearest $5%$5%). The results were:

$35%$35%, $40%$40%, $10%$10%, $30%$30%, $30%$30%, $15%$15%, $35%$35%, $30%$30%, $35%$35%, $35%$35%

Medium
4min
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Outcomes

12D.D.1.5

Interpret statistical summaries to describe the characteristics of a one-variable data set and to compare two related one-variable data sets; describe how statistical summaries can be used to misrepresent one-variable data; and make inferences, and make and justify conclusions, from statistical summaries of one-variable data orally and in writing, using convincing arguments

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