Unit 4 - Lesson 9 - Grade 8: Illustrative Mathematics

If you were babysitting, would you ratherCharge $5 for the first hour and $8 for each additional hour?OrCharge $15 for the first hour and $6 for each additional hour?Explain your reasoning.

Describe what is happening in each tank. Either draw a picture, say it verbally, or write a few sentences.

Use the table to estimate when the tanks will have the same amount of water.

The amount of water (in liters) in tank 1 after t minutes is 30t + 25 . The amount of water (in liters) in tank 2 after t minutes is -20t + 1000. Find the time when the amount of water will be equal.

What is the height of each elevator at this time?

How long would it take each elevator to reach ground level at this time?

If the two elevators travel toward one another, at what height do they pass each other?

How long would it take?

If you are on an underground parking level 14 meters below ground, which elevator would reach you first?

What does the equation 100 + 0.05p = 0.25p represent?