(a)  sf(k) = (n + d)k

      0.3 ´ 3k^.5 = (0.05 + 0.1)k

      0.9k^.5 = 0.15k

      0.9/0.15 = k/k^.5

      6 = k^.5

      k = 6² = 36

      y = 3k^.5 = 3 ´ 6 = 18

      c = y - (n + d)k = 18 - (0.15 ´ 36) = 12.6

(b)  sf(k) = (n + d)k

      0.4 ´ 3k^.5 = (0.05 + 0.1)k

      1.2k^.5 = 0.15k

      1.2/0.15 = k/k^.5

      8 = k^.5

      k = 8² = 64

      y = 3k^.5 = 3 ´ 8 = 24

      c = y - (n + d)k = 24 - (0.15 ´ 64) = 14.4

(c)  sf(k) = (n + d)k

      0.3 ´ 3k^.5 = (0.08 + 0.1)k

      0.9k^.5 = 0.18k

      0.9/0.18 = k/k^.5

      5 = k^.5

      k = 5² = 25

      y = 3k^.5 = 3 ´ 5 = 15

      c = y – (n + d)k = 15 - (0.18 ´ 25) = 10.5

(d)  sf(k) = (n + d)k

      0.3 ´ 4k^.5 = (0.05 + 0.1)k

      1.2k^.5 = 0.15k

      1.2/0.15 = k/k^.5

      8 = k^.5

      k = 8² = 64

      y = 4k^.5 = 4 ´ 8 = 32

      c = y – (n + d)k = 32 - (0.15 ´ 64) = 22.4