The binomial distribution formula is (nCx) • px • (1 - p)n - x
In this case p = 0.1 (probability of being 20 to 24 years old), and 1 - p = 0.9.
The total number selected is n, which is 6, and the number of successes for part (a) is 2.
So, (6C2) • 0.12 • (0.9) 4 = 0.098415.
For part (b), we need fewer than 2 to be between 20 and 24, which means 0 or 1. So we calculate both and add them together.
(6C0) • 0.10 • (0.9) 6 = 0.531441
(6C1) • 0.11 • (0.9) 5 = 0.354294
The sum of these two numbers is 0.885735.