Krishna
0

Step 1: Make use of the given information

            NOTE:      Defective pens = 12

                                  Good pens  = 132

                    Total number of pens = 12 + 132 = 144

              So,  number of possible outcomes = 144


Step 2: Find the probability that pen taken out is a good one

              Number of good pens = 132

                So, favourable outcomes = 132  


          The probability of getting a good pen  =   \frac{\text{Favourable outcomes}}{\text{total number of outcomes}}


                                                                        =  \frac{132}{144}

                                                                             =  \frac{11}{12}