Unit 4: Statistics and Probability

Topic 4.3: Measures of Spread and Outliers Questions

Practice 20 exam-style questions for IB Math AI SL Topic 4.3. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.

1find1 mark
True or false: the mode is the only average that can have multiple values for one dataset.
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2find2 marks
State whether the standard deviation can be negative. Justify.
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3find2 marks
Find the median of: 5, 12, 8, 14, 9, 17, 3, 11.
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4find3 marks
The mean of 5 numbers is 18. Four of them are 12, 15, 20, 22. Find the fifth number.
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5find2 marks
Frequency table: [0,5): 4, [5,10): 9, [10,15): 14, [15,20): 11, [20,25): 7. Identify the modal class and the estimated modal value (midpoint).
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6find2 marks
Find the variance of: 3, 5, 7, 9, 11.
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7find1 mark
State one limitation of the mode as a measure of central tendency.
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8find2 marks
In a school survey, students were asked their preferred sport. Football: 42, Basketball: 38, Tennis: 25, Swimming: 18, Other: 12. State the mode and explain why mean/median don''t apply.
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9find3 marks
For the frequency table: x = 1, 2, 3, 4, 5 with frequencies 2, 5, 8, 4, 1. Find the mean.
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10write down2 marks
The lengths (in minutes) of 42 podcast episodes are grouped as: [0,5): 7, [5,10): 19, [10,15): 11, [15,20): 5.

(a) Write down the modal class.

(b) Estimate the modal length using the midpoint of that class.
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11find1 mark
Find the mode of: 4, 7, 9, 12, 15, 18.
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12find3 marks
A frequency table records weekly hours of study: 2 hours: 5 students; 3 hours: 8 students; 4 hours: 10 students; 5 hours: 4 students; 6 hours: 3 students. Calculate the mean hours of study.
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13find1 mark
A data set has mean 50. If 12 is added to every value, find the new mean.
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14find2 marks
A teacher adds 5 marks to every student''s test score. If the original mean was 64, find the new mean.
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15find2 marks
A shoe shop records the sizes sold one afternoon: 7, 8, 8, 9, 9, 9, 10, 10, 11, 9, 8. Find the modal shoe size and state why the mode is the most useful average for a shop ordering stock.
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16find2 marks
A dataset has mean 70 and σ 5. Identify whether the value 85 is an outlier using the mean ± 2σ rule.
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17find2 marks
Find the mean of: 12, 15, 18, 22, 25, 28, 30.
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18find2 marks
A dataset has mean 20 with n = 8. Find the new mean if the value 30 is REMOVED.
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19find2 marks
Test scores in a small class: 65, 72, 65, 80, 65, 72, 80, 65, 88, 72. Find the mode.
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20find1 mark
For the dataset 5, 5, 5, 5, 5, find the standard deviation.
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