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35 multiple-choice questions and 26 flashcards on Measures of Center and Variability, about 23% of the 6th Math: Statistics & Probability bank. Every one carries a written rationale.
Measures of Center and Variability is one of 4 chapters in CoStudy's 6th Math: Statistics & Probability bank, and it holds 35 of the bank's 150 multiple-choice questions — roughly 23% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.
Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.
10 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.
Find the range of 14, 22, 8, 19, 30, 11.
Answer: A — 22
A) max − min = 30 − 8 = 22. B) The minimum. C) The maximum. D) A middle value, not the range.
A data set has no value occurring more than once. Its mode is:
Answer: B — There is no mode (or every value is technically tied)
Mode requires repetition. (A), (C), (D) misread.
The median of {2, 4, 6, 8, 10} is:
Answer: C — 6
C) Middle of 5 sorted values is the 3rd: 6. A/B) Adjacent values. D) Average of the two middle values; used only for even n.
Which measure of spread describes how each value differs from the mean on average?
Answer: A — Mean Absolute Deviation (MAD)
A) MAD is the average distance to the mean. B) Range uses only the two extremes. C) IQR is the spread of the middle 50%, not distance to mean. D) Mode is a center, not a spread.
Which of the following is NOT a measure of variability?
Answer: C — Median
C) Median is a center. A/B/D) Range, IQR, MAD all measure spread.
In the data set {12, 15, 18, 20, 22, 24, 30, 33}, Q1 is:
Answer: D — 16.5
D) Lower half is {12,15,18,20}; median of that = (15+18)/2 = 16.5. A) The 2nd value, not the median of the lower half. C) The largest in the lower half. B) The minimum.
For data 5, 5, 5, 5, 5, 100, the median is:
Answer: A — 5
Median = middle of 5,5,5,5,5,100 ordered, between 3rd and 4th = (5+5)/2 = 5. (B), (C), (D) misread.
To find a missing value when you know the mean: if the mean of 4 numbers is 10 and three are 8, 9, 12, the fourth is:
Answer: A — 11
Sum = 40. Known sum = 29. Missing = 11. (B), (C), (D) miscalculate.
A histogram differs from a bar graph because:
Answer: B — Histograms display continuous numerical data in equal-width intervals (bins); bars touch — unlike bar graphs which display categorical data with gaps between bars
Bin structure + continuous data + touching bars are histogram features. (A), (C), (D) misread.
Find the mean of 2, 4, 6, 8, 10, 12.
Answer: B — 7
42/6 = 7. (A), (C), (D) misread.
4 cards from the 26 in this chapter.
What are the 'measures of center'?
Mean, median, and mode. They describe a typical or middle value.
What if no number repeats — what's the mode?
There is no mode (or sometimes called 'no mode').
MAD stands for?
Mean Absolute Deviation — average distance of values from the mean.
Find the mean of 4, 6, 8, 10.
7. (Sum = 28; 28 ÷ 4 = 7.)
These are a sample. The full Measures of Center and Variability chapter runs 61 items with per-chapter progress tracking, on the web and in the iOS app.
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