Question:
A grocery store has 100 cartons of banana yogurt in stock.Each carton contains 12 cup of banana yogurts.The probability that a cup has fewer than 20 banana chunks in it is 10 %. So,What is the probability that between 15 and 25 (inclusive) cartons out of the 100 cartons have exactly 3 cups with fewer than 20 banana chunks?

Here is my answer, i use the binomial probability method to do my answer: b(15,100,0.1)+(16,100,0.1).........+(24,100,0.1)+(25,100,0.1). so, it is right or wrong'

yours
James(11-2-2000)

You are correct in using the binomial distribution for this problem. In the language that is commonly used, "success" is a carton with exactly 3 cups with fewer than 20 banana chunks in it, and you are to find the probability of between 15 and 25 successes in 100 trials. You have answered the problem as if 0.10 is the probability of success, but 0.10 is the probability that a cup has fewer than 20 chunks. Your solution is correct except that 0.1 needs to be replaced by the probability that a carton has exactly 3 cups with fewer than 20 banana chunks in it.