Let’s designate events:
A – “the first bulb will be non-standard”;
B – “the second bulb will be non-standard”.
Events A and B are dependent.
The probability that the first bulb is non-standard:
P = 3/16
The probability of the second light bulb being non-standard, provided that the first light bulb turned out to be non-standard, is
P = 2/15
It is taken into account that the total number of bulbs and the number of non-standard among them will decrease by one if the first light bulb is non-standard. According to the theorem of multiplication of probabilities for two dependent events
P = 3/16 * 2 * 15 = 1/40 = 0.025
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.