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A thermometer graduated according to a linear scale reads a value x0 when in contact with boiling water, and x0/3 when in contact with ice. What is the temperature of an object in °C, if this thermometer in the contact with the object reads x0/2?

1. 60
2. 35
3. 25
4. 40

Correct answer: 25

Solution

With R=aT+b, R(100)=x0 and R(0)=x0/3 give b=x0/3 and a=x0/150. Setting R=x0/2: x0/2 - x0/3 = (x0/150)T -> x0/6 = x0 T/150 -> T = 25 C.

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