Question

Question #0506c

Answer 1

Here for the unknown thermometer `X`

the lower fixed point or ice point, `L_x=30^@`
and steam point or upper fixed point, `U_x=170^@`

For Celcius thermometer we know,

the lower fixed point or ice point, `L_c=0^@`
and steam point or upper fixed point, `U_c=100^@`

Let the reading of `X` thermometer be `R_x` when Celcius thermometer reads `78^@`

The relation of two sacle is

#(R_x-L_x)/(U_x-L_x)= (R_c-L_c)/(U_c-L_c)#

#=>(R_x-30)/(170-30)= (78-0)/(100-0)#

#=>(R_x-30)/140= 0.78#

`=>R_x=0.78xx140+30=139.2^@`