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Chapter 10 Practice Paper: Data Analysis — Averages — mark scheme

QuizQuipPractice Series
QQ/S2MATH/CH10

Secondary 2 · Lower Secondary Mathematics (G2 / G3)

Mark scheme

Data Analysis — Averages

Chapter 10 Practice Paper · Maximum mark: 30

Notes for markers

  • Award one mark for each point marked [1], up to the marks shown for the part.
  • Accept answers worded differently that show the same understanding.
  • Units are required where the answer line shows one. ecf: allow an error carried forward.

Section A: Multiple-choice questions[10 marks]

QuestionAnswer
1BThe total is 24, and 24 ÷ 4 = 6.1
2AOrdered: 1, 3, 5, 7, 9 — the middle value is 5.1
3DThe value 4 occurs three times.1
4CTotal = mean × count = 15 × 8 = 120.1
5BAverage the middle pair: (14 + 16) ÷ 2 = 13.1
6AThe mean sums all values before dividing.1
7DEach leaf attaches to its stem: 35 and 38.1
8CTallest bar = highest frequency = modal class.1
9AA uniform shift moves the mean by the same amount.1
10BConsistency is about how tightly the scores pack together.1

Section B: Structured questions[20 marks]

QuestionAnswer and marking pointsMarks
1(a)

9 (it occurs three times) [1]

1
1(b)

Ordered: 9, 9, 9, 11, 12, 15, 20 — the 4th of 7 values is 11.

  • Values ordered [1]
  • Median 11 [1]
2
1(c)

Total 85, so 85 ÷ 7 ≈ 12.14.

  • Total 85 found [1]
  • ≈ 12.14 [1]
2
Total for Question 15
2(a)

6 × 74 = 444 [1]

1
2(b)

New total 7 × 75 = 525, so the 7th score is 525 − 444 = 81.

  • New total 525 [1]
  • 81 [1]
2
2(c)

(444 − 66) ÷ 5 = 378 ÷ 5 = 75.6.

  • 444 − 66 = 378 [1]
  • 75.6 [1]
2
Total for Question 25
3(a)

5, 8, 12, 14, 14, 19, 21, 26.

  • All eight values [1]
1
3(b)

The 4th and 5th values are 14 and 14, so the median is 14.

  • Middle two identified [1]
  • Median 14 [1]
2
3(c)

Total 119, so 119 ÷ 8 = 14.875 ≈ 14.9.

  • Total 119 used [1]
  • ≈ 14.9 [1]
2
Total for Question 35
4(a)

20 ≤ t < 30 minutes [1]

1
4(b)

18 + 12 = 30 [1]

1
4(c)

Midpoints 5, 15, 25, 35: (6×5 + 14×15 + 18×25 + 12×35) ÷ 50 = 1110 ÷ 50 = 22.2 minutes.

  • Midpoints 5, 15, 25, 35 used [1]
  • Weighted total 1110 [1]
  • Estimate 22.2 minutes [1]
3
Total for Question 45

— End of mark scheme —