6.1+Scaling+Up+or+Down+0910



Math 7B
==The Big Idea  Many important practical and mathematical applications involve comparing quantities of one kind or another; it is important to know which method to use and how we should use them. ==

Notes: A T-Rex weighed 8100 kilograms and was about 6 meters tall. The size of its skull is about 1 meter long and had 15-centimeter long incisors. A “larger than average human being weighs 90 kilograms and is 2 meters tall. A human’s skull is about 20 centimeters long and has incisors 1 centimeter long.


 * __Problem 6.1: Scaling Up or Down__**


 * Write a paragraph to help someone younger than you understand how the size of the T-Rex compares to the size of a human. Be very specific about the comparisons you are making.**

The T-Rex was one of the most fascinating creatures that weighed a massive 8100 kilograms. A human weighs about 90 kilograms, which means a T-Rex weighs 90 times more. A T-Rex was 6 meters tall while a human is only 2 meters tall. So if you put 3 humans on top of one another, they will be as tall as the T-Rex. It takes 5 human skulls to be as long as a T-Rex skull because a human skull is 20 centimeters long while a T-Rex’s is a full meter. You may think 15 centimeters is not very long, but for a tooth, it’s huge! If a human tooth is just 1 centimeter, just imagine how big the T-Rex’s 15-centimeter tooth is. That means its tooth is exactly 15 times longer. That’s how big the T-Rex was compared to a large human.


 * __Problem 6.1 Follow-Up__**


 * 1. ****Suppose an infant T-Rex was the same height as the human described in this problem and was similar to an adult T-Rex. What would be the scale factor between a grown T-Rex and an infant T-Rex?**

If an infant T-Rex is the same height as a large human, it’s 2 meters tall. The scale factor between the adult and infant is 1/3.


 * 2. ****How long were the incisors of this young T-Rex?**

Grown T-Rex’s incisors= 15cm Scale Factor=1/3 1/3 of 15cm=5cm So the length of the infant’s incisors is 5cm


 * 3. ****How long was the skull of this young T-Rex?**

Grown T-Rex’s skull=1 meter Scale Factor=1/3 1/3 of a meter=33cm So the length of the infant’s skull is 33 cm