A line graph shows the temperature of a metal rod being heated in a science experiment. At 0 minutes the temperature is 20°C. The temperature increases by exactly 8°C every minute. After how many minutes from the start will the temperature FIRST exceed 100°C?
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Worked Solution
Step 1: Write an expression for the temperature after t minutes.
Temperature = 20 + 8t
Step 2: Find when temperature first EXCEEDS 100°C (strictly greater than).
20 + 8t > 100
8t > 80
t > 10
Step 3: The smallest whole number of minutes greater than 10 is 11.
Step 4: Verify.
At t = 10: 20 + 80 = 100°C. Not exceeding (equal only).
At t = 11: 20 + 88 = 108°C. Exceeds 100°C. ✓
Answer: 11 minutes.
Correct answer: 11 minutes
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