A blanking disk 0.875 in thick is to be fastened to a spool whose flange is 1

Question:

A blanking disk 0.875 in thick is to be fastened to a spool whose flange is 1 in thick, using eight ½ in-13 X 1.75 in hex-head cap screws.
(a) What is the length of threads LT for this cap screw?
(b) What is the effective length of the grip l′?
(c) Is the length of this cap screw sufficient? If not, round up.
(d) Find the shank length ld and the useful thread length lt within the grip. These lengths are needed for the estimate of the fastener spring rate kb .