Work through the levels in order. Type your answer and press Check — open the worked solution if you get stuck. Answers like -6, 3/4 or 0.25 are typed exactly as shown. A ⭐ Bonus Challenge at the end is extra credit — skip it if the rest was hard work.
Level 1 · Warm-up
1 Frequencies are 4, 8, 5, 2, 1. How many data values are there altogether?
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20.
2 In a pets table, 8 students own 1 pet each. How many pets is that?
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8.
3 About how many class intervals should a grouped table have? (a range like 5-8)
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About 5 to 8.
Level 2 · Core
4 Pets: 0→4, 1→8, 2→5, 3→2, 4→1. How many students own 2 or more pets?
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5 + 2 + 1 = 8.
5 Same table. How many PETS are owned in total?
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0 + 8 + 10 + 6 + 4 = 28.
6 Heights: 150–154 → 4, 155–159 → 9. What is the cumulative frequency at 155–159?
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13.
Level 3 · Challenge
7 Is "0–9, 10–19, 20–29" a valid set of class intervals?
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Yes — same width, no overlap, no gaps.
8 Heights: 150–154 → 4, 155–159 → 9, 160–164 → 11, 165–169 → 5. How many are under 165 cm?
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4 + 9 + 11 = 24.
9 A cumulative frequency column reads 4, 13, 11, 30. What is wrong?
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It decreases (13 → 11). A running total can never go down.