4.2 Presentation of dataIB Maths: Analysis and Approaches SL: Flashcards

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Why are continuous classes written like $20 \le t < 40$?

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Why are continuous classes written like $20 \le t < 40$ ?: So there are no gaps or overlaps; every value belongs to exactly one class.
Which class does 40 belong to: $20 \le t < 40$ or $40 \le t < 60$ ?: $40 \le t < 60$
In an equal-width frequency histogram, what does bar height show?: The frequency of the class.
What is cumulative frequency?: The number of data items less than a given value (a running total).
Position of the median for grouped data with $n = 200$ ?: The 100th value.
Position of the 90th percentile when $n = 200$ ?: The 180th value.
Linear interpolation formula within a class?: $a + \frac{r}{f} \times w$ : start $a$ , $r$ items into a class of $f$ items and width $w$ .
What are the five numbers in a five-number summary?: Minimum, $Q_1$ , median, $Q_3$ , maximum.
$Q_1 = 30$ , $Q_3 = 50$ . Outlier boundaries?: $30 - 30 = 0$ and $50 + 30 = 80$ .
Where does a whisker end if there is an outlier?: At the most extreme data value that is not an outlier.
Median much closer to $Q_1$ than to $Q_3$ : what shape?: Positively skewed.
What box-plot shape suggests a normal distribution?: Symmetric: median central in the box and whiskers of similar length.
What should a comparison of two distributions include?: A measure of centre and a measure of spread, each interpreted in context.