The probability that all 4 widgets sold are defective is 0.00036, and the probability that none of the 4 widgets sold are defective is 0.55229.
How to find probability?
a) Probability that all are defective
There are 4 defective widgets and 25 non-defective widgets. If 4 widgets are sold at random, the probability that all of them are defective is:
P(all defective) = (4/29)(3/28)(2/27)(1/26)
= 0.00036
b) Probability that none are defective
There are 25 non-defective widgets and 4 defective widgets. If 4 widgets are sold at random, the probability that none of them are defective is:
P(none defective) = (25/29)(24/28)(23/27)(22/26)
= 0.55229
Therefore, the probability that all 4 widgets sold are defective is 0.00036, and the probability that none of the 4 widgets sold are defective is 0.55229.