Answer
(a) {ab, ac, ad, bc, bd, cd, ba, ca, da, cb, db, dc}
(b) {ab, ac, ad, ae, af, ag, ba, bc, bd, be, bf, bg, ca, cb, cd, ce, cf, cg, da, db, dc, de, df, dg, ea, eb, ec, ed, ef, eg, fa, fb, fc, fg, fd, fe, ga, gb, gc, gd, ge, gf}
(c) S = {gg, gd, dg, dd}
(d) S = {gd, dg, gg}
Work Step by Step
(a) The batch contains the items {a, b, c, d} is {ab, ac, ad, bc, bd, cd, ba, ca, da, cb, db, dc}
(b) The batch contains the items {a, b, c, d, e, f , g} which is 42 elements is {ab, ac, ad, ae, af, ag, ba, bc, bd, be, bf, bg, ca, cb, cd, ce, cf, cg, da, db, dc, de, df, dg, ea, eb, ec, ed, ef, eg, fa, fb, fc, fg, fd, fe, ga, gb, gc, gd, ge, gf}
(c) Let d and g denote defective and good, respectively. Then S = {gg, gd, dg, dd}
(d) S = {gd, dg, gg}
