D. Because the teachers are what matter in this survey.
i think the answer is 0.001853
Answer: 0.7748
Step-by-step explanation:
Given : Number of bit bulls at the pound = 18
Number of pit bulls have attacked another dog in the last year =4
The proportion of pit bulls have attacked another dog in the last year:
Number of the pit bulls selected = 6
The probability of that none of the pit bulls in Joe's group attacked another dog last year : 
By using binomial , the probability that at least one of the pit bulls in Joe's group attacked another dog last year is given by :-

Hence, the required probability = 0.7748
1/4 + 1/3 + 1/6 = 3/12 + 4/12 + 2/12 = 9/12 reduces to 3/4...leaving 1/4 for worker z.
answer is : 1/4 hrs was allocated to worker z