Solving 4th-grade math on pages 100 and 101, exercises 1,2,3,4,5 in the textbook

=> Reference Grade 4 Math Solutions here: Grade 4 Math Solutions
 

Guide to solving 4th-grade math on pages 100,101 in practice (including solving methods)
 

1. Solve 4th-grade math on pages 100,101 practice exercise 1

Solution method:
According to the area measurement unit table:
- Order of area measurement units: km²; hm²; dam²; m²; dm²; cm²; mm²
- Each area measurement unit is 100 times the value of the adjacent smaller unit
- Each area measurement unit is equal to 1/100 times the value of the adjacent larger unit.

2. Solve Grade 4 math on pages 100, 101 practice exercise 2 in the textbook

Problem:
Calculate the area of a rectangular land plot, knowing:
a) Length 5km, width 4km;
b) Length 8000m, width 2km.

Solution method:
- For part a): Apply the formula for the area of a rectangle: S = a x b (where S is the area; a is the length; b is the width)
- For part b): Convert the unit from meters to kilometers, then apply the formula for the area of a rectangle by multiplying the length by the width.

Answer:
a) The area of that land is:
5 x 4 = 20 (km²)
b) We have 8000m = 8km
The area of that land is:
8 x 2 = 16 (km²)
 

3. Solve Grade 4 practice exercises on pages 100, 101 in the textbook, exercise 3

Problem:
Given the areas of three cities (according to 2002 data) are:
Hanoi: 921km²
Da Nang: 1255km²
Ho Chi Minh City: 2095km²

Solution method:
Compare similar to comparing natural numbers; a number with more digits is greater than the others. In case the numbers have the same number of digits, compare the digits in the same position, and the number with a larger digit is greater.

4. Solve Grade 4 math exercises on pages 100, 101 practice exercise 4

Problem:
A rectangular plot of land has a length of 3km, and the width is 1/3 of the length. Calculate the area of that land

Solution method:
- Step 1: Calculate the width of the land by multiplying the length by 1/3
- Step 2: Calculate the area of that rectangular plot of land by multiplying the length by the width.

Answer:
The width of that plot is:
3 : 3 = 1 (km)
The area of that plot is:
3 x 1 = 3 (km²)
Answer: 3km²
 

5. Solve 4th-grade math on pages 100,101 practice exercise 5

Solution method:
Students observe the chart carefully and compare the questions with the information on the chart to answer all the requirements. 
- For question a): To know which city has the highest population density, students observe the chart, if any column is the highest, that is the city with the highest population density.
- For question b): To know how many times the population density of Ho Chi Minh City is compared to the population density of Hai Phong, we take the population density of Ho Chi Minh City divided by the population density of Hai Phong, the quotient is the number of times to find.

Answer:
a) Hanoi is the city with the highest population density (2952 people/km²).
b) The population density of Ho Chi Minh City is 2375 people/km².
The population density of Hai Phong is 1126 people/km²;
So we have: 2375 : 1126 = 2 remainder 123
So the population density of Ho Chi Minh City is about 2 times the population density of Hai Phong.

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Above is the section Solving 4th-grade math on pages 100 and 101 in the concise exercise book. Additionally, students can review the part Solving 4th-grade math on page 100 solved earlier or preview the part Solving 4th-grade math on pages 102,103 parallelogram to study Math in 4th grade better