Probability of Rain on Specific Days

In a certain city, the probability of rain on any given day in August is $0.3$. A local outdoor concert is scheduled for August 21st. Assuming each day's weather is independent of the others, what is the probability that it rains on exactly 2 days in the 21 days of August leading up to the concert?

Use the binomial probability formula:

$$P(X = k) = {n race k} p^k (1-p)^{n-k}$$

where:

• $n$ is the number of trials (days),
• $k$ is the number of successes (rainy days),
• $p$ is the probability of success (0.3 for rain).