A hole is to be drilled in the plate at A. The diameters of the bits available to drill the hole range from 1/2 to 11/2 in. in 1/4-in. increments. If the allowable stress in the plate is 21 ksi, determine
(a) the diameter d of the largest bit that can be used if the allowable load P at the hole is to exceed that at the fillets,
(b) the corresponding allowable load P.