Why do we multiply across the branches on probability tree diagrams and add down the column? How is the multiplication rule related to conditional probability?

At least two people have the same birthday in a school of 150 students

If 24 people have the flu out of 360 people, how many would have the flu out of 900. choose many ways you could use proportion that david would use to solve this problem

The price of a visit to the dentist is calculated according to the formula 50+100n50+100n where nn is the number of cavities the dentist finds. on your last visit to the dentist, 22 cavities were found. what was the cost of your visit?