Thank you for posting your question here at brainly. Below is the answer:
Shear strength of steel
= 0.75 800 10^6 N/m2
total load with safety factor
= 3000 5.6
= 16800 N
Cross section area needed
= 16800 / 0.75 800 10^6
= 28 10^(-6) m2
Diameter of bolt
= square root of [ 4 area / phi}
= sq root [ 35.65 10^ -6]
= 5.97 10^ -3 m
= 5.97 mm