## E.3 Answers to Lecture 3 tutorial

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### E.3.1 Answers to Sect. 3.1

Answers implied by H5P.

1. Volume of drinks in 375ml: Graph D.
Students sometimes say Graph A, because cans have very similar amounts.
2. Time in exam for short or easy exam: Graph C.
3. Time in exam for long or hard exam: Graph B.
4. The heights of females USC students: Graph D.
5. The starting salaries: Graph C.
Students sometimes say Graph B, thinking that salaries rise over time.

### E.3.2 Answers to Sect. 3.2

Answers implied by H5P.

You can have different groups (two or four) do different parts, and then explain their answers to other groups.

Promote discussion, don’t just give answers. Ask why!

### E.3.3 Answers to Sect. 3.3

1. Females Weddell: about 260–270 cm long, vary from about 200 to 310 cm. Slight negative skewness; possible small outlier at about 170–180 cm.
2. Dotchart. (Too much data for a useful stem-and-leaf plot probably.)
3. Better with a title; some more labelled tick marks would be better.

### E.3.4 Answers to Sect. 3.4

Have students work in groups, and then share their answers.

1. A few issues…
• The vertical axis is not labelled. Presumably burn time in seconds.
• The horizontal axis is not labelled. We have no way of knowing what is happening there.
2. A few issues…
• This is not a summary: This shows the burn-time of every individual candle. This makes it hard to compare means, which is the RQ.
• Why is every bar labelled? That just adds unnecessary clutter.
• Fonts are hard too read (small).
• A boxplot (or dotchart) would be the appropriate graph.
• The largest value is over 70 minutes! Do a quick project!
3. A few issues…
• Compares just two numbers (means) using lots of ink.
• No indication of variation in the data.
• A boxplot (or dotchart) would be appropriate.

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