# Constant Rate

Video solutions to help Grade 8 students learn how to define constant rate in varied contexts as expressed using two variables where one is t representing a time interval.

## New York State Common Core Math Module 4, Grade 8, Lesson 11

### Lesson 11 Student Outcomes

• Students know the definition of constant rate in varied contexts as expressed using two variables where one is t representing a time interval.
• Students graph points on a coordinate plane related to constant rate problems.

### Lesson 11 Summary

• When constant rate is stated for a given problem, then you can express the situation as a two variable equation. The equation can be used to complete a table of values that can then be graphed on a coordinate plane.

### NYS Math Module 4 Grade 8 Lesson 11 Examples & Exercises

Example 1
Pauline mows a lawn at a constant rate. Suppose she mows a 35 square foot lawn in 2.5 minutes. What area, in square feet, can she mow in 10 minutes? t minutes?

Example 2
Water flows at a constant rate out of a faucet. Suppose the volume of water that comes out in three minutes is 10.5 gallons. How many gallons of water comes out of the faucet in t minutes?

Exercises 1–3
1. Juan types at a constant rate. He can type a full page of text in 3 1/2 minutes. We want to know how many pages, p, Juan can type after t minutes.
a. Write the linear equation in two variables that represents the number of pages Juan types in any given time interval.
b. Complete the table below. Use a calculator and round answers to the tenths place.
c. Graph the data on a coordinate plane.
d. About how long would it take Juan to type a 5-page paper? Explain.

2. Emily paints at a constant rate. She can paint 32 square feet in five minutes. What area, A, can she paint in t minutes?
a. Write the linear equation in two variables that represents the number of square feet Emily can paint in any given time interval.
b. Complete the table below. Use a calculator and round answers to the tenths place.
c. Graph the data on a coordinate plane.
d. About how many square feet can Emily paint in 2 1/2 minutes? Explain.

3. Joseph walks at a constant speed. He walked to the store, one-half mile away, in minutes. How many miles, m, can he walk in t minutes?
a. Write the linear equation in two variables that represents the number of miles Joseph can walk in any given time interval, t.
b. Complete the table below. Use a calculator and round answers to the tenths place. c. Graph the data on a coordinate plane.
d. Joseph's friend lives miles away from him. About how long would it take Joseph to walk to his friend's house? Explain.