Probability

The probability that an accident occurs in a cloudy day is two times greater than in a sunny day. There were $20$ sunny days and $10$ cloudy days in April. In this month exactly one accident happened. What is the probability that this accident occurred in a sunny day?

We have a pack with $54$ cards. There are exactly four aces inside. We choose two cards from the package in a random manner without putting back. What is the probability that we choose two aces? Round your answer to $4$ decimal places.

We have randomly rolled the standard dice for $7$ times. The result was always number $3$. What is the probability that the next result will also be number $3$?

The probability of a student completing a medical degree is $0.3$. What is the probability that at least $2$ of $7$ students finish the university successfully? Round your result to $2$ decimal places.