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Lintel Sep 21 - 27 25 questions
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Monday 21 September 2026

Keystones #264 · Five questions · Open this day only

  1. 1. Number

    Express 144 as a product of prime factors

    Answer: 2⁴ × 3²
  2. 2. Algebra

    Solve: 2x + 3y = 35 and 3x - y = 14

    Answer: x = 7, y = 7
  3. 3. Geometry

    Find b if a = 11cm and c = 15cm

    Answer: 10.2cm
  4. 4. Ratio

    a:b is 3:5 and b:c is 5:4. Find a:b:c.

    Answer: 3:5:4
  5. 5. Statistics

    A fair coin is flipped 154 times. How many heads would you expect?

    Answer: 77

Tuesday 22 September 2026

Keystones #265 · Five questions · Open this day only

  1. 1. Number

    Express 100 as a product of prime factors

    Answer: 2² × 5²
  2. 2. Algebra

    Solve: 2x + 3y = 21 and 3x - y = 15

    Answer: x = 6, y = 3
  3. 3. Geometry

    Calculate the missing side: a = 18cm, c = 36cm

    Answer: 31.2cm
  4. 4. Ratio

    a:b is 2:3 and b:c is 1:2. Find a:b:c.

    Answer: 2:3:6
  5. 5. Statistics

    A fair coin is flipped 80 times. How many heads would you expect?

    Answer: 40

Wednesday 23 September 2026

Keystones #266 · Five questions · Open this day only

  1. 1. Number

    Express 120 as a product of prime factors

    Answer: 2³ × 3 × 5
  2. 2. Algebra

    Solve: 5x + 4y = 30 and 2x + 3y = 19

    Answer: x = 2, y = 5
  3. 3. Geometry

    Find b if a = 6cm and c = 15cm

    Answer: 13.75cm
  4. 4. Ratio

    a:b is 1:2 and b:c is 4:5. Find a:b:c.

    Answer: 2:4:5
  5. 5. Statistics

    A bag has 3 red out of 13 balls. If you pick 89 times (with replacement), how many times would you expect red?

    Answer: 20.5

Thursday 24 September 2026

Keystones #267 · Five questions · Open this day only

  1. 1. Number

    Write 36 as a product of its prime factors

    Answer: 2² × 3²
  2. 2. Algebra

    Solve: 3x + 5y = 16 and x + y = 4

    Answer: x = 2, y = 2
  3. 3. Geometry

    Find b if a = 13cm and c = 18cm

    Answer: 12.45cm
  4. 4. Ratio

    a:b is 3:2 and b:c is 1:2. Find a:b:c.

    Answer: 3:2:4
  5. 5. Statistics

    A fair coin is flipped 90 times. How many heads would you expect?

    Answer: 45

Friday 25 September 2026

Keystones #268 · Five questions · Open this day only

  1. 1. Number

    Express 180 as a product of prime factors

    Answer: 2² × 3² × 5
  2. 2. Algebra

    Solve: 2x + 3y = 30 and 3x - y = 1

    Answer: x = 3, y = 8
  3. 3. Geometry

    Calculate the missing side: a = 20cm, c = 27cm

    Answer: 18.cm
  4. 4. Ratio

    a:b is 1:2 and b:c is 3:4. Find a:b:c.

    Answer: 6:12:16
  5. 5. Statistics

    A bag has 4 red out of 13 balls. If you pick 98 times (with replacement), how many times would you expect red?

    Answer: 30.2