Amount of chips required to insure that a least 90% of the time 12 are nondefective Hi does anyone have any suggestions on how to solve this problem?

To construct a circuit a student needs, among others, 12 chips of a certain type.
The student knows that 4% of these chips are defective.
How many chips have to be provided so that, with a probability of not less than 0.9, the student has a sufficient number of nondefective chips in order to be able to construct the circuit?


Hint: The distribution of the number of good chips in the sample is binomial.  You'll probably just need a few more than 12, so try n=12, 13, 14, ...
