No. of good pens = 132

No. of defective pens = 12

Total no. of possible outcomes = 12 + 12 {total no of pens}

E ⟶ event of getting a good pen.

No. of favourable outcomes = 132 {132 good pens}

P (E) = (No.of favorable outcomes)/(Total no.of possible outcomes)

∴ P(E) = 132/144 = 66/72 = 33/36 = 11/12