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A steel tape reads correctly at 20 deg C. A piece of wood is measured with this steel tape at 0 deg C, and the tape reads 25 cm. The true length of the wood is:

1. 25 cm
2. less than 25 cm
3. greater than 25 cm
4. cannot say

Correct answer: less than 25 cm

Solution

Cooling the tape below 20 deg C shrinks its markings, so each centimetre mark is shorter; the tape therefore reads more than the true length.

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