## Key Concepts

- Use a bar diagram to solve a multiplication problem

### Solve word problems using multiplication

**What are the steps in solving word problems involving multiplication?**

- Read and understand the problem.

- Know what is asked.

- Find what the given parts are.

- Determine what operation to be used and take the word clue that will represent multiplication.

- Solve the problem.

- Verify the answer.

**Example:**

The monthly salary of a man is $2,625. Find the annual income.

**Solution:**

Monthly income = $2,625

Annual income = $2,625 × 12

Therefore, annual income = $31,500.[Text Wrapping Break]**3.7.1 Use a bar diagram to solve a multiplication problem**

### Bar diagram

Bar diagrams are the pictorial representation of data (generally grouped) in the form of vertical or horizontal rectangular bars.

**Example:**

Uncle Ray is 3 times as old as Lenin. Lenin is 13 years old. Find the age of Uncle Ray.

**Solution:**

What am I asked to find?

Let a = The age of the uncle.

Draw a bar diagram to represent the problem.

Write and solve the equation using the variable.

13 x 3 = a

39 = a

Uncle age = 39.

**Example 2:**

Charmin bought 6 Fun Fest tickets. Each one cost $135. What is the total cost?

**Solution:**

What am I asked to find?

Let p = The cost of 6 tickets.

Draw a bar diagram to represent the problem.

Write and solve equation using the variable.

$135 x 6 = p

$135 x 6 =$ 810

So, p =$ 810

6 Fun Fest tickets cost is $ 810.

**Example 3:**

Sharon’s Stationery store has 1,219 boxes of cards. May’s market has 3 times as many boxes of cards. Find the total cards May’s market have.

**Solution:**

What am I asked to find?

Let b= boxes of cards.

Draw a bar diagram to represent the problem.

Write and solve the equation using the variable.

1,219 x 3 = b

1,219 x 3 = 3,657.

May’s market has 3,657 boxes of cards.

## Exercise

- The capacity of a drum is 50 liters of milk. How much milk can be collected in 5 drums of such capacity?
- In a school, a fee of $1,345 is collected per student. If there are 24 students in a class, how much fee is collected from that class?
- A train has 14 coaches. In each coach, there are 172 seats. Find the total number of such seats on the train.
- Lenin bought a room-cooler. The cost of the room-cooler is $1958. Find the total cost of 5 such room-coolers.
- One watch costs $896. Find the cost of 10 such watches.
- 18 theaters are there at the mall. Each theater has 175 seats. How many seats are there in all?

- 2,456 x 7 = p. Find the value of p.
- 134 x 34=_______.
- 3,145 x 5 =_________.
- ____ x 98 =98,000

### Concept Map

### What have we learned

- Understand how to solve word problems.
- Identify bar diagram.
- Use a bar diagram to solve a multiplication problem.
- Understand how to solve equation using variable.

#### Related topics

#### Composite Figures – Area and Volume

A composite figure is made up of simple geometric shapes. It is a 2-dimensional figure of basic two-dimensional shapes such as squares, triangles, rectangles, circles, etc. There are various shapes whose areas are different from one another. Everything has an area they occupy, from the laptop to your book. To understand the dynamics of composite […]

Read More >>#### Special Right Triangles: Types, Formulas, with Solved Examples.

Learn all about special right triangles- their types, formulas, and examples explained in detail for a better understanding. What are the shortcut ratios for the side lengths of special right triangles 30 60 90 and 45 45 90? How are these ratios related to the Pythagorean theorem? Right Angle Triangles A triangle with a ninety-degree […]

Read More >>#### Ways to Simplify Algebraic Expressions

Simplify algebraic expressions in Mathematics is a collection of various numeric expressions that multiple philosophers and historians have brought down. Talking of algebra, this branch of mathematics deals with the oldest concepts of mathematical sciences, geometry, and number theory. It is one of the earliest branches in the history of mathematics. The study of mathematical […]

Read More >>#### How to Solve Right Triangles?

In this article, we’ll learn about how to Solve Right Triangles. But first, learn about the Triangles. Triangles are made up of three line segments. These three segments meet to form three angles. The lengths of the sides and sizes of the angles are related to one another. If you know the size (length) of […]

Read More >>
Comments: