The runs scored by two batsmen in 5 matches are A: 40, 50, 60, 70, 80 and B: 45, 50, 50, 55, 50. Find the coefficient of variation for each. Who is more consistent?

1. 1 · Write what is given and what is to be found Five scores for each batsman. To find: the C.V. of each and the more consistent player.
2. 2 · Write the formulas x̄ = Σx/n; σ = √(Σd²/n) with d = x − x̄; C.V. = (σ/x̄) × 100%.
3. 3 · Work out batsman A
   • x̄ = 300/5 = 60; d: −20, −10, 0, 10, 20; Σd² = 1000
   • σ = √(1000/5) = √200 ≈ 14.14
   • C.V. = (14.14/60) × 100% ≈ 23.57%
4. 4 · Work out batsman B
   • x̄ = 250/5 = 50; d: −5, 0, 0, 5, 0; Σd² = 50
   • σ = √(50/5) = √10 ≈ 3.16
   • C.V. = (3.16/50) × 100% ≈ 6.32%
5. 5 · Compare 6.32% is less than 23.57%, so B's scores vary much less compared with his average.
6. 6 · Check and box the answer C.V. of A ≈ 23.57%, C.V. of B ≈ 6.32%. Batsman B is more consistent.

Scoring tip: Always end with a one-line conclusion, such as: B is more consistent because his C.V. is smaller. It carries a mark.