Solve Word Problems Using Multiplication

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? 

1. Read and understand the problem. 

2. Know what is asked. 

3. Find what the given parts are. 

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

5. Solve the problem. 

6. 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.