Statistical data
Answers are for parents and teachers.
1
For the series 2, 5, 3, 2, 4, 2, 5, 3, 2, 4, 3, 2 write the variation series and the frequency table. Which variant has the largest frequency?
2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 5. Frequencies: 2 → 5, 3 → 3, 4 → 2, 5 → 2 (sum 12). The variant 2 has the largest frequency.
2
The lifetimes (hours) of 80 bulbs: 0–100 → 4, 100–200 → 12, 200–300 → 32, 300–400 → 24, 400–500 → 8. What percentage last from 200 to 400 hours?
(32 + 24)/80 = 56/80 = 70 %.
3
Which are quantitative: favourite subject, number of books read, shoe size, class number?
The number of books read, the shoe size and the class number are quantitative; the favourite subject is qualitative.
4
The population is 5000 students and the sample is 250. What percentage of the population is the sample?
250/5000 = 0.05 = 5 %.
5
Why are the intervals of a histogram taken with equal length?
With equal bases the height (frequency) and the area of a bar are proportional, so bars can be compared directly. With different widths a taller bar need not mean a larger frequency.