a) 0.5
b) 1
c) 0.97
d) 2

Answer: a
Explanation: diameter of bolt = 20mm, diameter of hole = 20+2 =22mm
e=1.5×22=33mm, p=2.5×20=50mm
e/3d₀ = 33/(3×22) = 0.5, p/3d₀ -0.25 = 50/(3×22) -0.25=0.5, f_ub /f_b = 400/410=0.975
k_b = minimum of (e/3d₀ , p/3d₀ -0.25, f_ub /f_b, 1) = 0.5.