Math 137
Instructor Reyes
Module 12 Homework Key
Interpret the meaning of the slope and the y-intercept in context for each of the following in
complete sentences for the following examples.
1. The cost of hiring a private tutor is $20 plus an additional $4 per hour. The equation representing
this information is given by C= 20+4h.
a. Slope: (m= 4, interpret this in context)
Sentence: For each additional hour of tutoring the cost increases $4.
b. Y-intercept: (b=20, interpret this in context)
Sentence: When the hours of tutoring are zero, when there is no tutoring, the (base) cost will be
$20.
2. Max bought a car for $25,000. It will depreciate by $3000 per year. The equation representing this
is : V= 25000-3000t.
a. Slope = - 3000
Sentence: For each additional year the value of the car decreases by $3000.
b. Y-intercept = 25000
Sentence: In year zero, when the car was first bought, the value was $25000.
3. A tree is planted with an initial height of 12 feet. It will grow about 2 feet per year. The equation
representing this information is given by H=12+2t
a. Slope = 2
Sentence: For each additional year, the tree grows 2 feet.
b. Y-intercept = 12
Sentence: When the year was zero, which is when the tree was planted, the height was 12 feet.