Answer
a) y | p(y)
25 | 0.8
100 | 0.15
300 | 0.05
E(y) = ∑ y . p(y)
E(y) = 25 × 0.8 + 100 × 0.15 + 300 × 0.05
E(y) = 50
average class size equal to E(y) = 50
b) y | p(y)
25 | 
100 | 
300 | 
E(y) = ∑ y . p(y)
E(y) = 25 × 0.4 + 100 × 0.3 + 300 × 0.3
E(y) = 130
average class size equal to E(y) = 130
c) Average Student in the class in a school = 50
Average student at the school has student = 130
Answer:
About 4 hours.
Step-by-step explanation:
Let's set up a proportion and cross multiply.

Cross multiply.
120 = 28x
Divide by 28 on both sides.
= 4.28571428571
Round this to the nearest whole number, which is just 4. The answer is about 4 hours.
Answer: x = 108
Step-by-step explanation: In this problem, we're given a diagram and
we're asked to find the value of x that would make m ll n.
We can see that the angles that are marked in the diagram
are same-side interior angles since they lie on the same side
of the transversal and they lie on the interior of lines m and n.
Therefore, in order for line m to be parallel to line n,
these angles must be supplementary.
In other words, they must add to 180 degrees.
So we can setup the equation x + 72 = 180.
Subtracting 72 from both sides gives us x = 108.
So the value of x that would make line m ll n is 108.