Solution:

Quantities of pens = Numbers of blemished pens + Numbers of good pens

∴ Total number of pens = 132+12 = 144 pens

P(E) = (Number of great results/Total number of results)

P(picking a decent pen) = 132/144 = 11/12 = 0.916

Solution:

Quantities of pens = Numbers of blemished pens + Numbers of good pens

∴ Total number of pens = 132+12 = 144 pens

P(E) = (Number of great results/Total number of results)

P(picking a decent pen) = 132/144 = 11/12 = 0.916