How do we use interpolation in thermodynamics water or steam tables?

Question

how do we use it and how it works

Answer 1

For every value of X there must be a value in Y and there must be a linear relation between X&Y then if
X1-----------------> Y1
X4-----------------> Y4 suppose we need the value of Y at X=X3 Which is not given in the table and X3 lies between
X1&X4. tofind out the value at X=X3
find out (Y4-Y1)/(X4-X1) let it be P. Then find out X3-X1
(If X3>X1)
suppose X3-X1 =q then the value of Y at X=X3 is Y1+( pxq)

Answer 2

Depends on the specific table. Suppose you want to know the saturation pressure of steam at 107 deg C. Your table may tell you the saturation pressure at 100 and 110 deg C. So you estimate the pressue at 7/10th of the difference plus the 100 degree value.