Lecture 13 Bernoulli’s Formula. The Most Probable Number of Occurrences of an Event If n

What is the probability of the drawn ball being blue?

Solution. Let A be the event of drawing a blue ball. After a ball was drawn from the second box and placed into the first, two collections of balls have turned out in the first box:

1. 
   8 blue and 7 red balls it contained prior to replacement;
   
2. 
   one ball replaced from the second box.
   

The probability of appearance of a blue ball belonging to the first collection is and from the second collection, .

The probability that he randomly drawn ball belongs to the first collection is and to the second, .