Question 62829
The probability of one calculator having no defects is 30/46. When a second is chosen the probability of having no defects is 29/45. The probability of no defects in the third is 28/44 and in the fourth is 27/43.

The probability of no defects in any of the calculators is found by multiplying the individual probabilities together.
{{{(30/46)*(29/45)*(28/44)*(27/43)=0.168}}}
The probability of all calculators having no defects is 16.8%. The probability of at least one defect is the complement of that probability.  
ie an 83.2% probability of at least one defect.