Worked Example 1
Twenty students were asked how many brothers and sisters they have.
The raw data2, 1, 3, 0, 2, 4, 1, 2, 3, 1, 0, 2, 2, 5, 1, 3, 2, 1, 4, 2
Tally through the list onceRead in order, tallying in fives
The finished table0:2, 1:5, 2:7, 3:3, 4:2, 5:1
Check the total2+5+7+3+2+1 = 20, matching the students asked. Always do this check.
Worked Example 2
Forty test marks run from 12 to 67. Design suitable classes.
Find the rangeRange = 67 − 12 = 55
Choose the number of classes55 ÷ 6 is about 9, so use a class size of 10
Write the classes10–19, 20–29, 30–39, 40–49, 50–59, 60–69
Check for overlaps and gapsAfter 19 comes 20: nothing missed, nothing repeated.
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