The spring constant for a helical coil spring is predicted by:

where G is the material modulus, d is the wire diameter, D is the mean diameter of the coil and na is the number of coils.

Assume the following spring properties and measurements.

G $=74$ kN$/$mm$2$ d $=1700$ microns

OD $=29$ mm na $=74$ coils

Also assume that each of the above properties and measurements have an error or uncertainty of $3\mathrm{.}8\%.$

Use the High$-$Low method to estimate the error or uncertainty in the prediction of the sprig constant, Ep in N$/$m$.$

Recall the coil mean diameter D is slightly different from the outside coil diameter OD$.$ Report the result with at least $3$ significant figures.