☰ Year plan · Mathematics

Dispersion and standard deviation

Week 14 · Measures of dispersion: range, interquartile range and standard deviation for a list, a frequency table and a table with class intervals · 3 lessons
Answers are for parents and teachers.
1
Find the range, Q₁, Q₂, Q₃ and IQR of 2, 5, 8, 9, 13, 14, 20.
2
Find σ for 2, 3, 5, 7, 8 to 2 decimal places.
3
Scores x = 2, 3, 4, 5 with frequencies 1, 2, 4, 3. Find the mean and σ.
4
Classes 0–, 10–, 20–, 30– with f = 3, 6, 7, 4. Find σ.
5
Two bakeries make bread weighing on average 500 g. Bakery 1 has σ = 4 g and bakery 2 has σ = 12 g. Which sells more even loaves, and why?