In Molimba, the heights, in cm, of adult males are normally distributed with mean 176cm and standard deviation 4.8 cm.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.

1. [M1] Using ± standardisation formula with 170, 176 and 4.8 substituted appropriately. Condone σ² and √σ. No continuity correction.
2. [M1] Appropriate area Φ, from final process, must be a probability. Expect final answer > 0.5.
3. [A1] 0.894 or 0.89435 < p < 0.8944. If A0 scored, SC B1 for 0.894 or 0.89435 < p < 0.8944, WWW.
4. [M1] 1-their 3(a) seen or implied by 0.7056 or 0.2944
5. [B1] 0.540 <z ≤0.541 or -0.541 < z < 0.540 seen.
6. [M1] Use of standardisation formula with k, 176, 4.8 equated to a z-value (not 1.25, 0.7601, 0.2399, 0.7056, 0.7257, 0.8313, 0.253±0.894, 0.6, 0.4), not 4.8², not √4.8, no continuity correction.
7. [A1] CAO (answer required to 1 dp).