**Basics
**The formula provided for total cost by the Mathematics Formula Sheet is straightforward, but it can be rearranged to ask questions about price per unit and number of units, too.

A question involving total cost is often a plug-in (where you end up plugging in numbers for words).

The word *per* is a hint that a cost-related question could be coming.

**Formulas (Mathematics Formula Sheet)**

Total Cost = [Number of Units] × [Cost Per Unit]

**Formulas (NOT on Mathematics Formula Sheet)**

Cost Per Unit = [Total Cost] ÷ [Number of Units]

Number of Units = [Total Cost] ÷ [Cost Per Unit]

Question

A bakery charges $0.79 per doughnut. What is the total cost of 12 doughnuts?

**Answer
**$9.48

**Answer Process**

[Number of Units] = 12 doughnuts

[Cost Per Unit] = $0.79 per doughnut

Total Cost = [Number of Units] × [Cost Per Unit]

Total Cost = 12 × 0.79 = 9.48

Input |
Display |
Comment |

blinker | clears screen | |

12 × 0.79 | 12*0.79 | Total Cost = Number of Units × Cost Per Unit |

9.48 | Answer | |

## Total Cost |

**
Question
**A crew worked from 6 AM to 7 PM replacing a faulty roof at a cost of $8,124.22. How much was the crew paid per hour?

**Answer
**$624.94 per hour

**Answer Process**

[Total Cost] = $8124.22

[Number of Units] = 6 AM to 7 PM = 13 hours

Cost Per Unit = [Total Cost] ÷ [Number of Units]

Cost Per Unit = 8124.22 ÷ 13 = 624.94

Input |
Display |
Comment |

blinker | clears screen | |

8124.22 ÷ 13 | 8124.22÷13 | Cost Per Unit = Total Cost ÷ Number of Units |

624.94 | Answer | |

## Total Cost: Cost Per Unit |

**
Question
**A concession stand sold $375.00 worth of popcorn. The popcorn cost $1.25 per bag. How many bags of popcorn did the concession stand sell?

**Answer
**300 bags

**Answer Process**

[Total Cost] = $375.00

[Cost Per Unit] = $1.25 per bag

Number of Units = [Total Cost] ÷ [Cost Per Unit]

Number of Units = 375.00 ÷ 1.25 = 300

Input |
Display |
Comment |

blinker | clears screen | |

375.00 ÷ 11 | 375.00÷1.25 | Number of Units = Total Cost ÷ Cost Per Unit |

300 | Answer | |

## Total Cost: Number of Units |

Practice – Questions

1. A chili supper is held at a cost of $5.00 per person. What is the total cost of 150 people?

2. A fast food restaurant charges 99 cents per hamburger. What is the total cost of 25 hamburgers?

3. Bob rented a snowmobile from 7 AM to 6 PM at a cost of $244.75. What was the rental cost per hour?

4. Betty rented a car for 5 days at a cost $199.75. What was the rental cost per day?

5. A celebrity earned $5050.00 signing autographs. The celebrity charged $50.00 per autograph. How many autographs did the celebrity sign?

**
Practice – Answers
**1. $750.00

2. $24.75

3. $22.25 per hour

4. $39.95 per day

5. 101 autographs