Beginner Level:
Step-by-Step Solution
1. Analyze the Conditions:
l From condition 1, A did not bring an apple, so A must have brought either a banana or an orange.
l From condition 2, B brought a banana. Therefore, A could not have brought a banana, meaning A brought an orange.
l From condition 3, C did not bring an orange. Thus, C must have brought an apple.
2. Apply Hints to Draw a Conclusion:
l B brought the banana, A brought the orange, and C brought the apple.
3. Final Answer:
l A brought an orange, B brought a banana, and C brought an apple.
Intermediate Level:
Step-by-Step Solution
1. Analyze the Conditions:
l From condition 1, A ordered after B.
l From condition 2, C was the last to place an order.
l From condition 3, D ordered at 10 a.m., so D is likely the first to order.
l From condition 4, A ordered after D, meaning A cannot be the first to order.
2. Evaluate Conditions in Sequence:
l Based on condition 3, D ordered first.
l From condition 1, A ordered after B, so A must come after B.
l From condition 2, C ordered last, making C the fourth in sequence.
3. Find the Possible Order:
l If D is first and C is last, A and B must occupy the second and third spots.
l From condition 1, A comes after B. Thus, B is second and A is third.
4. Conclusion:
l The order of the customers is D → B → A → C.
Advanced Level:
Step-by-Step Solution
1. Analyze the Conditions:
l The airline owns five planes, each with a maximum capacity of 150 passengers.
l All five cities must have at least one flight per week.
l Weekly passenger demand for each city is as follows:
① City A: 200 passengers
② City B: 300 passengers
③ City C: 500 passengers
④ City D: 150 passengers
⑤ City E: 250 passengers
2. Calculate Flight Requirements by City:
l City A: Needs 200 passengers → requires two planes (one plane can only carry 150 passengers).
l City B: Needs 300 passengers → requires two planes.
l City C: Needs 500 passengers → requires four planes.
l City D: Needs 150 passengers → requires one plane.
l City E: Needs 250 passengers → requires two planes (one plane for 150 passengers, another for the remaining 100 passengers).
3. Adjust for Plane Limitations and Optimize Allocation:
l With only five planes available, prioritize cities based on passenger demand to maximize revenue.
l Allocate as follows:
① City C receives two planes (300 passengers).
② City A receives one plane (150 passengers).
③ City B receives one plane (150 passengers).
④ City D receives one plane (150 passengers).
l City E is deprioritized due to plane constraints but could be partially serviced later if resources allow.
4. Final Allocation and Conclusion:
l City C: 2 planes (300 passengers)
l City A: 1 plane (150 passengers)
l City B: 1 plane (150 passengers)
l City D: 1 plane (150 passengers)