WAEC 2018 Mathematics · Question 3
If F = C + 32, find C when F = 98.6
Options
- A.30
- B.37
- C.39
- D.41
Answer: B. 37
Explanation written with AI and checked against the answer key
Analyze the question: This is the Celsius-to-Fahrenheit conversion formula. We are given F and asked to find C, so we must make C the subject of the formula. Concept: To find C, undo the operations in reverse order: first subtract 32, then divide by 9/5, which means multiplying by 5/9. Solution: F = (9/5)C + 32 Substitute F = 98.6: 98.6 = (9/5)C + 32 Subtract 32 from both sides: 98.6 − 32 = (9/5)C 66.6 = (9/5)C Multiply both sides by 5/9: C = 66.6 × 5/9 C = 333/9 C = 37 Check: (9/5)(37) + 32 = 66.6 + 32 = 98.6 ✓ Tip: Normal human body temperature is 37°C, or 98.6°F. If you remember this pair, you can spot the answer quickly. For converting from F to C, the shortcut formula is C = (5/9)(F − 32). Also, when a question gives a decimal like 98.6, subtract first and then multiply. This keeps the arithmetic simple.AI can make mistakes. Report anything that looks wrong.
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