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Maths · Grade 6 · Set C
Choosing With Care
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C
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Goal: 15 min
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Remember: Check for a far dot before you choose. A far dot pulls the mean but barely moves the median.

Read the dots

1
Circle every statement that is true about this data.
The mean is 8The median is 8One dot is far from the restThe median is 9
2
There are 8 dots. What is the median? Find the number halfway between the middle two. Answer:
3
What is the mean of this data? The dots add to 58. Answer:
4
Seven of the eight dots are 7 or less. Which number tells the story of a typical value better?
The median, 5.5The mean, 7.25
5
Taking the far dot away moves the mean more than it moves the median.
TrueFalse

What a far dot does

6
The top plot is the data. The bottom plot is the same data after one far dot joins. Which number does NOT change?
The meanThe rangeThe median
7
After the far dot joins, there are 10 dots that add to 74. What is the new mean? Answer:
8
Circle every plot where the median is the better pick.
Plot APlot BPlot C
9
Both classes have a mean of 6. The top plot is Class A and the bottom plot is Class B. Which class has dots that are more spread out?
Both the sameClass AClass B
10
Join each situation to the best number to report.
  1. 1Most homes cost about the same, but one is a castle
  2. 2Quiz scores bunched evenly around 80
  3. 3How spread out the middle half of the data is
  • Athe mean
  • Bthe median
  • Cthe IQR

Stretch

11
Five friends read for 6, 7, 7, 8 and 22 minutes. The mean is 10 and the median is 7. Which number tells how long a typical friend reads?
The mean, 10 minutesThe median, 7 minutes
12
Make up a set of 6 numbers where the median is a better pick than the mean. Write why.
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Answer key · Set C
Choosing With Care
1The mean is 8, The median is 8 The dots add to 72 and 72 ÷ 9 = 8. The 5th dot is 8. No dot is far from the rest.
25.5 The 4th dot is 5 and the 5th dot is 6. Halfway between them is 5.5.
37.25 58 ÷ 8 = 7.25.
4The median, 5.5 The mean, 7.25, is above all seven of the bunched dots because of the far dot. The median, 5.5, sits in the crowd.
5True Without the dot at 23 the mean drops from 7.25 to 5. The median only moves from 5.5 to 5.
6The median The mean goes from 6 to 7.4 and the range from 4 to 16. The median stays at 6.
77.4 74 ÷ 10 = 7.4.
8Plot B, Plot C B and C each have one dot far from the rest. A is balanced, so the mean is fine.
9Class B Class A runs from 5 to 7, a range of 2. Class B runs from 2 to 9, a range of 7.
101-B, 2-A, 3-C A far value pulls the mean, so use the median. Balanced data lets you use the mean. The IQR is the spread of the middle half.
11The median, 7 minutes Four of the five friends read 8 minutes or less. The median, 7, matches them. The mean, 10, is higher than four of the five.
12Your own words: a grown-up reads it.
Mark each answer, count the right ones and write the score on the sheet.