? No — wrong; Index is not average.
Actually: only if index units are moment/constant and the constant is the same. Let’s test option a: DOI 114.8. easa atpl question bank
Crew added index = 114.8 – 112.4 = 2.4. Then 2.4 = (410 × arm)/CF → CF = (410 × 142)/2.4 ≈ 24,258 — not round. Let’s test option a: DOI 114
Index formula typically: , but in this question bank, they provide index directly for BEM and arm values for others. We must compute additional moment index from crew: Index formula typically: , but in this question
Wait — option a says DOI = 114.8 → difference = 2.4. That means Crew index = 2.4. Then 2.4 = (410 × 142) / CF → CF = (410 × 142) / 2.4 ≈ 24,258. So CF = 24,258. Then BEM index = (34,560 × arm_BEM) / 24,258 = 112.4 → arm_BEM = (112.4 × 24,258) / 34,560 ≈ 78.9 m — plausible.
Now crew moment = 410 kg × 142.0 m = 58,220 → Crew Index = 58,220 / 10,000 = 5.822 ≈ 5.8.
a) 34,970 kg / 114.8 b) 34,970 kg / 115.2 c) 35,130 kg / 114.8 d) 35,130 kg / 115.2 Explanation: Step 1 – Calculate Dry Operating Mass (DOM) DOM = BEM + Crew & Crew Baggage + (other fixed operational items if any – here none except crew) DOM = 34,560 kg + 410 kg = 34,970 kg