Chapter 12: Ratio and proportion

In certain situations, comparison by division makes better sense than comparison by taking the difference. The comparison by division is called the ratio of the two numbers.

Introduction

In certain situations, comparison by division makes better sense than comparison by taking the difference. The comparison by division is called the ratio of the two numbers. In this chapter we will introduce the concept of ratios and proportions.
Introduction to ratios
What a ratio is. Simple ratio problems.

Ratio

Comparing any two quantities in terms of ‘how many times’ is known as ratio, and it is denoted by a ':' sign.Two quantities can be compared only if they are in the same unit. In this topic we will learn to simplify rations, and see how they are used through several basic examples.
Intro to ratios
Learn how to find the ratio between two things. In this video, we find the ratio of apples to oranges.
Ratios as fractions
How are fractions and ratios the same? How are they different? Is 2:5 the same as 2/5?
Basic ratios
Choose the ratio that goes with a picture of two quantities like apples and bananas. 
Ratios as fractions in simplest form
Ratios as Fractions in Simplest Form
Simplifying rates and ratios
Simplifying Rates and Ratios
Rational number word problem: computers
In this word problem, we'll compare the weight of two objects using a ratio of integers. We'll practice simplifying a fraction, too.
Rational number word problem: stock
Use your knowledge of proportions and fractions to determine shareholders profit in this word problem.
Ratio word problem: boys to girls
Sal solves a tricky ratio word problem.
Ratio word problem: centimeters to kilometers
Sal uses ratios to figure out how far apart two cities should be on a map.
Ratio word problems
Practice solving ratio word problems like, "If Ben reads 10 pages in 15 minutes, how long does it take him to read 40 pages?"
Solving ratio problems with tables example 1
We're displaying ratios in a table format here, and then asking: given a ratio, solve for equivalent ratios. Here are a few examples to practice on.
Solving ratio problems with tables example 2
Let's compare 2 tables of ratios and interpret them to solve the word problem. This is a fun!
Ratio tables
Practice filling out tables of equivalent ratios.