Question 366980
{{{1 - ((matrix(2,1,18,0))*(matrix(2,1,35,4)))/((matrix(2,1,53,4)))=0.82119}}}. How? The event that at least 1 calculator is defective is complementary with the event that no calculator is defective.  Hence 
P(at least 1 calculator is defective) = 1 - P(no calculator is defective).
But  P(no calculator is defective) = {{{((matrix(2,1,18,0))*(matrix(2,1,35,4)))/((matrix(2,1,53,4)))}}}, and hence the answer above.  (Note: This is an example of a hypergeometric probability distribution.)