Answer:
Step-by-step explanation:
Given that a school has 20 classes: 16 with 25 students in each, three with 100 students in each, and one with 300 students for a total of 1000 students.
a) Y = no of students in the class out of 20 selected at random
Y can take values as
Y 25 100 300 Total
freq 16 3 1 20
P(Y) 16/20 3/20 1/20 1
y*p 20 15 15 50
E(Y) = 50
b) X = size of student from which one student is taken at random
X 25 100 300 Total
No of classes 16 3 1 20
Total students
(X*no of classes) 400 300 300 1000
P(x) 0.4 0.3 0.3 1
X*P 160 90 90 240
E(x) =240
c) On an average, a student at this school is in a class with 240 students. On average, a class at this school has 50 students.
i.e. expectation of number of students in a class is 50 while expectation of a student having students in the class is 240
seconds to reach its maximum height.
feet.