There are 4 boys and 12 students in total. It would be 4/12, but if it was to be simplified, it would be 1/3. The probability of a boy being selected is 1/3.
Complete Question
The complete question is shown on the first uploaded image
Answer:
The probability is 
Step-by-step explanation:
From the question we are told that
The number of cars packed is 
The objective of this solution is to find the probability that the car which has a sunroof also has four doors
This probability is mathematically represented as

Baye's Rule define this probability mathematically as

From the diagram

and 
So

Sara can make 8 bouquets, with 3 yellow flowers and 2 red ones in each bouquet. How pretty !