- Ratios and Unit Rates
- Home
- Writing Ratios Using Different Notations
- Writing Ratios for Real-World Situations
- Identifying Statements that Describe a Ratio
- Simplifying a Ratio of Whole Numbers: Problem Type 1
- Simplifying a Ratio of Decimals
- Finding a Unit Price
- Using Tables to Compare Ratios
- Computing Unit Prices to Find the Better Buy
- Word Problem on Unit Rates Associated with Ratios of Whole Numbers: Decimal Answers
- Solving a Word Problem on Proportions Using a Unit Rate
- Solving a One-Step Word Problem Using the Formula d = rt
- Function Tables with One-Step Rules
- Finding Missing Values in a Table of Equivalent Ratios
- Using a Table of Equivalent Ratios to Find a Missing Quantity in a Ratio
- Writing an Equation to Represent a Proportional Relationship

- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who

# Function Tables with One-Step Rules

A **function table** has values of **input** and **output** and a **function rule**. In the function rule, if we plug in different values for the input, we get corresponding values of output. There is always a pattern in the way input values (x) and the output values (y) are related which is given by the function rule.

A function table is also called an **input-output table**. It can be drawn as a vertical table or horizontally as shown

x | y |

0 | 0 |

1 | 3 |

2 | 6 |

3 | 9 |

or

x | 1 | 2 | 3 | 4 | 5 |

y | 5 | 10 | 15 | 20 | 25 |

For **example**, a rule can be written as ‘add 2’ meaning add 2 to the input to get the output or it can be taken as ‘multiply by 4’ meaning multiply the input by 4 to get the output and so on.

Such rules can also be expressed using an equation as follows.

y = x + 2; y = 4x and so on.

Determine what one-step rule is used in the function table below.

In | Out |

15 | 21 |

18 | 24 |

21 | 27 |

### Solution

**Step 1:**

21 = 15 + 6; 24 = 18 + 6; 27 = 21 + 6; or output = input + 6

**Step 2:**

So, the rule is ‘Add 6’ to input to get output.

Determine what one-step rule is used in the function table below.

In | Out |

13 | 20 |

16 | 23 |

19 | 26 |

### Solution

**Step 1:**

20 = 13 + 7; 23 = 16 + 7; 26 = 19 + 7; or output = input + 7

**Step 2:**

So, the rule is ‘Add 7’ to input to get output.

Determine what one-step rule is used in the function table below.

In | Out |

35 | 21 |

38 | 24 |

41 | 27 |

### Solution

**Step 1:**

21 = 35 − 14; 24 = 38 − 14; 27 = 41 − 14;

**Step 2:**

So, the rule is ‘Subtract 14’ to input to get output.