X,Y and Z represent 20%, 30% and 50% 2%, 3% and 5% of students from X, Y and z (respectively)

the probability is 0.4%

Step-by-step explanation:

the probability is equal to the proportion of students of X respect to the total amount of students , assuming that each student is equally likely to be chosen, thus:

Probability = number of students of X that participate / total amount of students  = number of students of X / total amount of students * number of students of X that participate / number of students of X = 0.2 * 0.02 = 0.004 (0.4%)

c

Step-by-step explanation: