Problem $4.$ Concrete mix design Problem $(60$ points$)$The specific compressive strength $($or design strength$)$ of concrete, fc $=4500$ psi. The concrete is used for casting $3(1)/(2)$ inch thick slab and the spacing between reinforcement bars in the slab will not less than $12$ inch. Type I cement will be used for mixing concrete $($Fill answer in following blank$)1.$ What is the slump required for the concrete?$(5$ points$)2.$ What is the maximum size of coarse aggregate that can be used for the concrete?$(5$ points$)3.$ If the slab is supposed to be exposed to environment, should be non$-$air$-$entrained concrete with $1\%$ air content or air$-$entrained concrete with air content of $5\%$ selected for the project?$(5$ points$)4.$ What is the amount of water in lbs$.$ should be used for mixing $1$ cubic yard concrete?$(5$ points$)5.$ What is the maximum permissible water$/$cement ratio $($w$/$c$)$ that can be used for mixing concrete?$(5$ points$)$