SSC JE Civil Engineering 25-Sep-2019 Shift 1 Solved Paper

Shear strength of one rivet in single shear.
${\mathit{P}}_{\mathrm{ss}}=\mathit{n}\times 1\times \frac{\mathit{\pi }}{4}{\left(\mathit{d}\right)}^2$ (per pitch n = 1)
n = number of rivets per pitch
shear strength of double riveted double cover built joint.
${\mathit{P}}_{\mathrm{sd}}=\mathit{n}\times 2\times \frac{\mathit{\pi }}{4}{\left(\mathit{d}\right)}^2$ (per pitch n = 2)
$=2\times 2\times \frac{\mathit{\pi }}{4}{\left(\mathit{d}\right)}^2\left({\mathit{n}}^1=2\right)$
$=4\times \frac{\mathit{\pi }}{4}{\left(\mathit{d}\right)}^2$
${\mathit{n}}_1=4.{\mathit{P}}_{\mathrm{ss}}\Rightarrow {\mathit{P}}_{\mathrm{sd}}=\mathit{n}.{\mathit{P}}_{\mathrm{ss}}$
n = 4
Hence option (a) is correct.