WAEC 2018 · Paper 2 · Q3
| Price (₦1,000,000) | 1.0–1.9 | 2.0–2.9 | 3.0–3.9 | 4.0–4.9 | 5.0–5.9 |
|---|---|---|---|---|---|
| Number of vehicles | 23 | 48 | 107 | 90 | 32 |
The frequency distribution shows the range of prices of a brand of car sold by a dealer and the corresponding quantity demanded.
- (a)
Represent the information in a histogram.
Model answer
Draw bars on the class boundaries, not the class limits (0.95, 1.95, …, 5.95 million), with no gaps between them. The height of each bar is the frequency, and each axis is labelled.
To estimate the mode, take the tallest bar. Join its top-left corner to the top-left corner of the bar on its right, and its top-right corner to the top-right corner of the bar on its left. Read down from where the two lines cross: the mode is about 3.7 million naira.
- (b)
Use the histogram to determine the most preferred selling price for the brand of car (in millions of naira).
Try it on a graph
Histogram with the crossed lines that locate the mode.
Worked solution (try it first)
(a)
- The prices are in classes, so draw a histogram.
- The class 1.0–1.9 really runs from 0.95 to 1.95, so mark the boundaries on the horizontal axis.
- Draw touching bars of heights .
- Label the axes "Price (₦ million)" and "Number of vehicles".
(b)
- The most preferred price is the one bought most often: the mode.
- It's in the tallest bar, 2.95–3.95.
- Join the top-left corner of that bar to the top-left corner of the next bar, and the top-right corner to the top-right corner of the bar before.
- Read down from where the lines cross: about 3.7, so about ₦3,700,000.
- By formula, as a check:million.