Answer:
k = 4
Explanation:
The formula for binomial probability distribution is;
P(X = k) = C(n, k) × p^(k) × (1 - p)^(n - k)
Where C(n, k) is the number of possible ways that n number of people choose k.
While p is probability of success
In this question, 20 children want to choose from 4 toys namely tricycle, blocks, a train set, and puzzles.
This means that from binomial probability distribution formula, n = 20 and k = 4.