CAT Exam Numerical Ability Age Problem

a shopkeeper received a pack of 15 pen out of which 4 were defective.the shopkeeper decided to examine every one one by one by selecting a pen at random .the pen examined are not put back.what is the probability that the ninth one examined is the last defective pen
options 11/195 b) 16/195 c)8/195 d)17/195

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CAT Other Question
the number 1,2,3......40 are written on blackboard. the following operation is then repeated 39 times .in each repetition any two number say and b currently on the blackboard are erased and a new number a+b-1 is written what will be the number left on the blackboard at the end.
options
a) 820 b)821 c)781 d)819 e)780 In the expression xy2,the values of both variables x and y are decreased by 20%.By this,the value of the expresssion is decreased by