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Guidelines for solving exercises from page 21 of Math 5, including solving methods
1. Solve exercise 1 on page 21 of Math 5 textbook
Problem Statement:
A person buys 25 notebooks, priced at 3000 dong each, spending all their money. With the same amount, if the person buys notebooks priced at 1500 dong each, how many notebooks can they buy?
Solution Method:
- Calculate the amount of money the person has by multiplying the number of notebooks needed to buy by the price of 1 notebook.
- Calculate the number of notebooks the person can buy at 1500 dong/ 1 notebook by dividing the person's available money by the price of 1 notebook (1500 dong).
Answer:
The person's amount of money is:
3000 x 25 = 75,000 (dong)
The number of notebooks purchasable at 1500 dong each is:
75,000 : 1500 = 50 (notebooks)
Answer: 50 notebooks
2. Solve exercise 2 on page 21 of Math 5 textbook
Problem Statement:
A family consists of 3 members (father, mother, and one child). The average monthly income is 800,000 dong per person. If the family has one more child and the total income remains unchanged, how much does the average monthly income per person decrease?
Solution Method:
- Step 1: Find the total income of the family by multiplying the average monthly income per person by 3 (people)
- Step 2: To find the average income per person if there is one more child, divide the total family income by 4 (people)
- Step 3: Find the amount by which the average monthly income per person decreases when adding another child by subtracting the total income from the average income per person when adding one more child (result from step 2).
Answer:
The family's monthly income is:
800,000 x 3 = 2,400,000 (dong)
If there is one more child, the average income per person will be:
2,400,000 : (3 + 1) = 600,000 (dong)
The decrease in average income per person is:
800,000 - 600,000 = 200,000 (dong).
3. Solve exercise 3 on page 21 of Math 5 textbook
Problem Statement:
A team of 10 people digs 35 meters of trench in a day. If an additional 20 people join to dig, how many meters of trench will be dug in a day? (The digging rate per person remains the same).
Solution Method:
- Step 1: Find the number of meters of trench dug in 1 day by 20 people by multiplying the number of meters dug in 1 day by 20, then divide by 10.
- Step 2: To find the total meters of trench dug by the team in a day, add the meters dug by the original team of 10 people to the meters dug by the additional 20 people.
Answer:
In a day, 20 people dig:
35 x 20 / 10 = 70 (m)
In a day, the entire team digs:
35 + 70 = 105 (m)
Answer: 105 meters.
4. Solve exercise 4 on page 21 of Math 5 textbook
Problem Statement:
A truck can only carry 300 bags of rice, each weighing 50 kg. If it loads bags of rice weighing 75 kg each, how many bags can the truck carry?
Solution Method:
- Find the total weight of rice the truck has carried by multiplying the number of bags of rice by the weight of each bag.
- Find the number of bags of rice weighing 75 kilograms the truck can carry by dividing the total weight the truck can carry by the weight of each bag.
Answer:
The total weight of rice the truck has carried is:
50 x 300 = 15,000 (kg)
The number of bags weighing 75 kg is:
15,000 : 75 = 200 (bags)
Concise guide to solving exercises on page 21 Math 5
Solve exercise 1 on page 21 Math 5 textbook
A person buys 25 notebooks, priced at 3000 dong each, spending all their money. With the same amount, if the person buys notebooks priced at 1500 dong each, how many notebooks can they buy?
Solution:
The person's amount of money is:
3000 x 25 = 75,000 (dong)
The number of notebooks purchasable at 1500 dong each is:
75,000 : 1500 = 50 (notebooks)
Answer: 50 notebooks.
Solve exercise 2 on page 21 Math 5 textbook
A family consists of 3 members (father, mother, and one child). The average monthly income is 800,000 dong per person. If the family has one more child and the total income remains unchanged, how much does the average monthly income per person decrease?
Solution:
The family's monthly income is:
800,000 x 3 = 2,400,000 (dong)
If there is one more child, the average income per person will be:
2,400,000 : (3 + 1) = 600,000 (dong)
The decrease in average income per person is:
800,000 – 600,000 = 200,000 (dong)
Chapter II introduces us to decimal numbers, where the concept of decimal numbers is widely used. Let's explore the hints for solving exercises on page 34, 35 Math 5 textbook to excel in Math grade 5.
A team of 10 people digs 35 meters of trench in a day. If 20 more people join, how many meters of trench can they dig in a day? (Each person digs at the same rate). Solution: With 20 people in a day: 35 * 20 / 10 = 70 (m) Total for the day with the whole team: 35 + 70 = 105 (m)
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Here are the full detailed solutions to Exercise on page 21 of Math 5 textbook. Prepare for the Exercise Focus on page 22 of Math 5 textbook through Exercise Solutions on page 22, 23 Math 5 and Review: Length Measurement Table through Exercise Solutions on page 22, 23 Math 5 to improve your Math 5 skills.
In addition to the above content, you can explore Exercise Solutions on page 57 of Math 5 textbook to enhance your knowledge of Math 5.
Furthermore, Exercise Solution on page 62 of Math 5 textbook is a crucial lesson in the Math 5 curriculum that students must pay special attention to.
