Please I need help with this ASAP. A teacher is playing a game with her students. She prepared 23 cards. Each card has a number from 1 to 23. She has 30 students in her class. She will pick 4 students from the class and ask them to draw 4 cards. Each student will pick one card only. These 4 numbers will create a secret code to a locker.
a) What is the probability that the secret code is composed of numbers with GCD 4?
b) If her top four students picked the numbers, what is the probability of getting at least 3 prime numbers?