$2\mathrm{.}2$ Two identical fatigue specimens $($denoted A and C $)$ are fabricated from a nonferrous alloy. Each is subjected to one of the maximum$-$minimum stress cycles listed below; the frequency is the same for all three tests.

$($a$)$ Rank the fatigue lifetimes of these two specimens from the longest to the shortest.

$($b$)$ Now justify this ranking using a schematic $\backslash (\backslash$mathrm$\{$S$\}-\backslash$mathrm$\{$N$\}\backslash )$ plot for both specimens $($A and C$).$ Here, just plot the approximative curve.