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.
