b$)$ A tensile$-$testing apparatus is to be constructed that must withstand a

maximum load of $220,000N.$ The design calls for two cy lind rical support posts,

each of which is to support half of the maximum load. Furthermore, plain$-$

carbon $(1045)$ steel ground and polished shafting rounds are to be used; the

minimum yield and tensile strengths of this alloy are $310$ MPa and $565$ MPa $,$

respectively. Specify a suitable diameter for these support posts