Histograms, box plots and choosing a display
Answers are for parents and teachers.
1
Make a frequency table for 31, 45, 28, 52, 39, 47, 35, 22, 41, 38, 56, 33, 44, 27, 36, 49 with the intervals 20–29, 30–39, 40–49, 50–59.
20–29: 3. 30–39: 6. 40–49: 5. 50–59: 2. Check: 3 + 6 + 5 + 2 = 16 values.
2
Write the five-number summary of 5, 8, 10, 12, 15, 17, 20.
Median 12. Lower half 5, 8, 10: Q1 = 8. Upper half 15, 17, 20: Q3 = 17. Summary: 5, 8, 12, 17, 20.
3
Find the median of 14, 9, 21, 11, 17, 25.
In order: 9, 11, 14, 17, 21, 25. The median is (14 + 17) ÷ 2 = 15.5.
4
In this box plot of the minutes that pupils read, between which two numbers is the middle half of the data? What are the minimum and the maximum?
The middle half is between Q1 = 15 and Q3 = 26. The minimum is 12 and the maximum is 34.
5
Which display would you use to show the prices of 300 books, and why?
A histogram, because there are many values and we want to see the overall shape in groups.