Key idea: this is an estimation question involving cascading adjustments — you must track both the gains and losses for the target applicant based on the actions of their neighbors.
Step 1: identify the target applicant and their neighbors.
The queue is: 10, 20, 30, 40, 50, 60, 70, 80.
The target is the 3rd applicant (initial score 30).
The person immediately ahead is the 4th applicant (initial score 40).
The person immediately behind is the 2nd applicant (initial score 20).
Step 2: calculate the target's gain.
The target (30) has an initial score < 40, so they are eligible to boost.
They boost by 50% of the person ahead's initial score (40).
Gain = 50%×40=20.
Step 3: calculate the target's loss.
The person behind the target (2nd applicant, initial score 20) also has an initial score < 40, so they are eligible to boost.
They boost by 50% of the target's initial score (30).
Because the 2nd applicant boosts, the target (the person immediately ahead of them) loses 20% of their own initial score.
Loss = 20%×30=6.
Step 4: calculate the final score.
Final score = Initial score + Gain - Loss
Final score = 30+20−6=44.
Common trap: forgetting that the target also loses points because the person behind them is eligible to boost.
Answer: 44