The average temperature on Wednesday, Thursday and Friday was 25°. The average…
2024
The average temperature on Wednesday, Thursday and Friday was 25°. The average temperature on Thursday, Friday and Saturday was 24°. If the temperature on Saturday was 27°, what was the temperature on Wednesday?
- A.
24°
- B.
21°
- C.
27°
- D.
30°
Show answer & explanation
Correct answer: D
Concept: When two groups of items overlap (share some common members), the sum of the shared members can be isolated by subtracting a known individual value from one group's total, then used to work back to an unknown individual value in the other group. Sum = Average × Count.
Total temperature for Wednesday, Thursday and Friday = 25° × 3 = 75°.
Total temperature for Thursday, Friday and Saturday = 24° × 3 = 72°.
Since Saturday = 27°, the combined Thursday + Friday total = 72° − 27° = 45°.
Wednesday's temperature = 75° − (Thursday + Friday) = 75° − 45° = 30°.
Cross-check: With Wednesday = 30°, Thursday+Friday = 45°, and Saturday = 27°: (30+45)/3 = 25° ✓ matches the first average, and (45+27)/3 = 24° ✓ matches the second average.