Answer:
Part A) see the explanation
Part B) 
Step-by-step explanation:
Part A)
we know that
A relationship between two variables, x, and C, represent a proportional variation if it can be expressed in the form
or 
Let
C ---> is the total cost (represent the output or dependent variable)
x ----> is the number of books (represent the input or independent variable)
In this problem
we have a proportional relationship between the variables x and C
Part B) we know that
The linear equation is given by

The constant of proportionality k is the same that the slope or unit rate of the linear equation
In this problem the constant k is given

so

For x=12 books
substitute in the equation and solve for C

In function notation

5 + 0.50p = 6.50
0.50p = 6.50 - 5
0.50p = 1.50
p = 1.50/0.50
p = 3 <=== the vehicle had 3 people in the vehicle
Answer:
Probability of atleast one of 12 student has food allergies ≈ 0.58 ( approx)
Step-by-step explanation:
Given: Probability of a children under age 5 has food allergies = 7%
=
To find : Probability of atleast one of 12 student has food allergies
Probability of a chindren under age 5 does not have food allergies = 
⇒ prob = 
now we find Probability of atleast one of 12 student has food allergies this means we have to find prob of 1 student, 2 student, 3 student, till 12 student have allergy out of 12 student of class then add all prob.
But instead of finding all these probability we find probability of student having no allergy.i.e., 0 student then subtract it from 1(total probability)
Probability of 0 student having allergy out of 12 student = 
Therefore, Probability of atleast one of 12 student has food allergies
= 
= 
≈ 0.58 ( approx)
Answer:
b: 44%
Step-by-step explanation:
From grades 9-10 there are 55 students who like country music.
While there are 125 grades 9-10 students in total.
This gives us a percentage of (55/125) *100% = 44%