A consolidated$-$drained $($CD$)$ triaxial test is performed on a $3-$inch diameter cohessionless sand sample. The sample is consolidated under a confining stress of $30,$ which is maintained throughout the test. Failure occurred when the deviator test load reached $678\mathrm{.}58lbs.$ Determine the major and minor principal stresses, the shear strength parameters $(\frac{O}{?}$ and $c)$ and the shear and normal stresses at failure.