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Lintel May 4 - 10 25 questions
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Monday 4 May 2026

Keystones #124 · Five questions · Open this day only

  1. 1. Number

    A value is 71.4 (to dp). State the error interval

    Answer: 71.35 ≤ x < 71.45
  2. 2. Algebra

    Expand: (x - 7)(x - 3)

    Answer: x² - 10x + 21
  3. 3. Geometry

    A circle has area 254.5cm². Find its radius (dp)

    Answer: 9cm
  4. 4. Ratio

    Express 28 as a percentage of 164

    Answer: 17.07%
  5. 5. Statistics

    Find the mean, mode, median and range of: 40, 34, 40, 24, 40

    Answer: Mean = 35.6, Mode = 40, Median = 40, Range = 16

Tuesday 5 May 2026

Keystones #125 · Five questions · Open this day only

  1. 1. Number

    70 is rounded to the nearest integer. What is the error interval?

    Answer: 69.5 ≤ x < 70.5
  2. 2. Algebra

    Expand: (x + 2)(x - 5)

    Answer: x² -3x - 10
  3. 3. Geometry

    Calculate the area of a circle with diameter 8cm

    Answer: 50.27cm²
  4. 4. Ratio

    Express 41 as a percentage of 113

    Answer: 36.28%
  5. 5. Statistics

    Find the mean, median and range of: 43, 26, 35, 72, 77, 57, 93

    Answer: Mean = 57.6, Median = 57, Range = 67

Wednesday 6 May 2026

Keystones #126 · Five questions · Open this day only

  1. 1. Number

    A value is 52.5 (to dp). State the error interval

    Answer: 52.45 ≤ x < 52.55
  2. 2. Algebra

    Expand: (x + 3)(x - 7)

    Answer: x² -4x - 21
  3. 3. Geometry

    A circle has area 201.cm². Find its radius (dp)

    Answer: 8cm
  4. 4. Ratio

    Express 45 as a percentage of 285

    Answer: 15.79%
  5. 5. Statistics

    Find the mean, median and range of: 11, 49, 80, 46, 60, 58, 33, 49

    Answer: Mean = 48.3, Median = 49, Range = 69

Thursday 7 May 2026

Keystones #127 · Five questions · Open this day only

  1. 1. Number

    95 is rounded to the nearest integer. What is the error interval?

    Answer: 94.5 ≤ x < 95.5
  2. 2. Algebra

    Expand: (x - 5)(x - 7)

    Answer: x² - 12x + 35
  3. 3. Geometry

    Calculate the area of a circle with diameter 18cm

    Answer: 254.47cm²
  4. 4. Ratio

    Express 49 as a percentage of 208

    Answer: 23.56%
  5. 5. Statistics

    Find the mean, mode, median and range of: 20, 35, 29, 29, 44

    Answer: Mean = 31.4, Mode = 29, Median = 29, Range = 24

Friday 8 May 2026

Keystones #128 · Five questions · Open this day only

  1. 1. Number

    73 is rounded to the nearest integer. What is the error interval?

    Answer: 72.5 ≤ x < 73.5
  2. 2. Algebra

    Expand: (x - 3)(x - 3)

    Answer: x² - 6x + 9
  3. 3. Geometry

    Calculate the area of a circle with diameter 20cm

    Answer: 314.16cm²
  4. 4. Ratio

    Express 50 as a percentage of 271

    Answer: 18.45%
  5. 5. Statistics

    Find the mean, mode, median and range of: 35, 12, 34, 40, 34

    Answer: Mean = 31, Mode = 34, Median = 34, Range = 28