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1. Solving exercise 1 on page 28 of Math textbook for grade 5
Problem:
Find the average of the following numbers:
a) 96; 121 and 143. b) 35; 12; 24; 21 and 43
Solution method:
>>> Refer to the detailed guide on how to calculate the average of multiple numbers in the part Solving exercise 1 on page 27 of Math textbook for grade 5.
Answer:
a) 96; 121 and 143
The sum of three numbers is: 96 + 121 + 143 = 360
The average of 96; 121 and 143 is: 360 : 3 = 120
b) 35; 12; 24; 21 and 43
The sum of five numbers is: 35 + 12 + 24 + 21 + 43 = 135
The average of 35; 12; 24; 21 and 43 is: 135 : 5 = 27
2. Solving exercise 2 on page 28 of Math textbook for grade 5
Problem:
The population of a commune increased by 96 people, 82 people, and 71 people respectively over 3 consecutive years. How many people does the population of the commune increase on average each year?
Solution method:
* Observation:
- Known quantities: The population increased by 96, 82, and 71 over 3 consecutive years
- To find: The average annual increase in population
* Solution:
- Step 1: Calculate the total increase in population over 3 consecutive years by adding the 3 known numbers
- Step 2: Calculate the average annual population increase = total increase in population : 3 (years).
Answer:
The total population increase of the commune over 3 consecutive years is: 96 + 82 + 71 = 249 (people)
The average annual population increase is: 249 : 3 = 83 (people)
Answer: Therefore, the commune increases by an average of 83 people each year
3. Solving exercise 3 on page 28 of Math textbook for grade 5
Problem:
The heights of 5 students in Class Four are respectively 138 cm, 132 cm, 130 cm, 136 cm, 134 cm. What is the average height of each student in meters?
Solution method:
* Problem Analysis:
- Given: Heights of 5 students are: 138; 132; 130; 136; 134 (cm)
- Required: Calculate the average height of each student.
* Solution:
- Calculate the total height of 5 students by adding all known heights together
- Calculate the average height of each student by: Taking the total height : 5 (students).
Answer:
The total height of 5 students is: 138 + 132 + 130 + 136 + 134 = 670 cm.
The average height of each student is: 670 : 5 = 134 cm
Answer: 134 cm
4. Solving exercise 4 on page 28 of Math textbook for grade 5
Problem:
There are 9 trucks transporting food into the city, among them 5 trucks go first, each truck can transport 36 tons and 4 trucks behind, each truck can transport 45 tons. What is the average amount of food each truck can transport?
Solution method:
* Observation:
- The problem states:
+ There are 9 trucks transporting food into the city
+ 5 trucks go first, each truck can transport 36 tons
+ 4 trucks behind, each truck can transport 45 tons
- The problem requires: Calculate the average tons of food each truck can transport.
* Solution:
- Step 1: Find the tons of food 5 trucks go first can transport by: Multiplying the tons of food each truck can transport by 5 (trucks).
- Step 2: Similarly, find the tons of food 4 trucks behind can transport by: Multiplying the tons of food each truck can transport by 4 (trucks).
- Step 3: Find the total tons of food 9 trucks can transport by: Adding the results from step 1 and step 2.
- Step 4: Find the average tons of food each truck can transport by: Dividing the total tons of food 9 trucks can transport (just found) by 9 (trucks).
- Step 5: Convert the unit from tons to tons and conclude.
Answer:
The five trucks going first can transport tons of food:
5 x 36 = 180 (tons).
The four trucks behind can transport tons of food:
4 x 45 = 180 (tons).
The total food transported by 9 trucks is:
180 + 180 = 360 (tons)
The average food each truck can transport is:
360 : 9 = 40 (tons) = 4 (tons).
Answer: 4 tons.
5. Solving exercise 5 on page 28 of Math textbook for grade 5
Problem:
a) The average of two numbers is 9. Knowing one of the two numbers is 12, find the other number.
b) The average of two numbers is 28. Knowing one of the two numbers is 30, find the other number.
Solution method:
* General Observation:
- The problem states:
+ The value of the average of two numbers
+ The value of one of the two numbers
- The problem requires: Find the other number.
* General Solution:
- Let the unknown number be represented by a variable (x, y, z, ...)
- Apply the calculation of the average: Average = (Unknown number + Known number) : 2
- Substitute the known values into the above formula, transform into a problem of finding the unknown (x, y, z, ...), carefully compute to find the correct result.
Answer:
a) Let the number to be found be x.
According to the problem, we have: (x + 12) : 2 = 9.
So the sum of the two numbers is: x + 12 = 9 x 2 = 18.
Hence, the number to be found is: x = 18 - 12 = 6.
Answer: x = 6.
b) Let the number to be found be y.
According to the problem, we have: (y + 30) : 2 = 28.
So the sum of the two numbers is: y + 30 = 28 x 2 = 56.
Hence, the number to be found is: y = 56 - 30 = 26.
Answer: y = 26.
After completing the solutions for Grade 4 Math Exercises 1, 2, 3 on page 27 of the textbook - Finding the average number as mentioned in the previous article. Solving grade 4 math problems to find the average number is not too difficult, however, when applying the materials Solve Math 4 page 28 Textbook - Practice, Find the average number, you can completely rest assured when reviewing, consolidating knowledge or doing math. With specific problem-solving guides from question 1 to 5 on page 28 of Math 4 textbook, it is presented clearly and easy to understand. Hopefully, students will find the method of solving math problems and studying math to achieve the highest results. In the next lesson, we will together refer to the content of solving Grade 4 math problems on page 29 Textbook - Charts, you guys should follow the next article to understand what charts are, how to draw charts.
Solve questions 1 to 5 on page 28 Mathematics textbook for Grade 4
- Solve question 1 on page 28 Mathematics textbook for Grade 4
- Solve question 2 on page 28 Math textbook for Grade 4
- Solve question 3 on page 28 Math textbook for Grade 4
- Solve question 4 on page 28 Math textbook for Grade 4
- Solve question 5 on page 28 Math textbook for Grade 4
Here is the solution to exercises on page 28 Math textbook for Grade 4 in the section of math exercises solutions for Grade 4. Students can review the solution to exercises on page 27 Math textbook for Grade 4 solved earlier or preview the solution to exercises on page 29 Math textbook for Grade 4 to improve their understanding of Grade 4 Math.
In Chapter 2 of Grade 4 Math, students will learn basic arithmetic operations such as addition, subtraction, multiplication, and division. To excel in Grade 4 Math, students can refer to the hints for solving exercises on page 39 Math textbook for Grade 4 about addition and the hints for solving exercises on page 40 Math textbook for Grade 4 about subtraction.
