Science and Mathematics for Engineering 6th Edition by John Bird

Exercise 4

The resistance $\mathrm { R }$ ohms of a copper wind ing is measured at various temperatures $t ^ { \circ } \mathrm { C }$ and the results are as follows:
$$\begin{array} { l l l l l l } \mathrm { R } ( \Omega ) & 38 & 47 & 55 & 62 & 72 \\\mathrm { t } \left( { } ^ { \circ } \mathrm { C } \right) & 16 & 34 & 50 & 64 & 84\end{array}$$
Plot a graph of $\mathrm { R }$ (vertically) against t (horizontally) and find from it
(a) the temperature when the resistance is $50 \Omega$
(b) the resistance when the temperature is $72 ^ { \circ } \mathrm { C }$
(c) the gradient
(d) the equation of the graph .