Question

A faulty thermometer has its fixed points marked as 5° and 95° The temperature of a body as measured by the faulty thermometer is 59°. What is the correct temperature of the body on Celsius scale ?
1. 59°C
2. 62.1°C
3. 56.05 °C
4. 60°C

Answer 1

Correct Answer - Option 4 : 60°C

Concept:

Fixed points of a thermometer are the freezing point and the boiling point of water, i.e. 0°C and 100°C 

Temperature variation of any other scale can be written as

T = ax + b

Where x = Temperature in °C, a,b = Constants

Calculation:

Given:

Freezing point of the given scale = 5°, Boiling point of the given scale = 95° 

Using T = ax + b

5 = a × 0 + b

⇒ b = 5

Now the equation becomes

T = ax + 5

Again using T = ax + 5

95 = a × 100 + 5

⇒ a = 0.9

Hence the equation is T = 0.9x + 5

For 59° 

59 = 0.9x + 5

x = 60°C