1. Two (different) quantities, one of which changes and the other changes accordingly. If the ratio of the corresponding two numbers in these two quantities must be a quotient, these two quantities are called (correlation quantities) and the relationship between them is called (proportional relationship).
2. (actual distance): (distance on the map) = scale. When the scale is fixed, the distance on the map is proportional to the actual distance.
3. Two fifths of the number A and three fourths of the number B are equal, number A: number B = (15: 8), and number A and number B are in (positive) proportion.
The area of a circle is directly proportional to its (square of radius).
5. If 5A=4B(A and B are not zero), then A and B are in (positive) proportion.
6.x and y are in direct proportion. Please fill in the form completely.
X 2 (2.4) quarter
Y 3 3.6 ( 3/8)
Second, ask questions.
The production process of a loom is as follows.
Working hours (hours) 1 2 3 4 5
Total workload (m) 16 32 48 64 80
(1) What are the two quantities in the table? Are they related?
There are two quantities, working hours and total work, which are in direct proportion.
(2) Write the ratio of several groups of numbers corresponding to two quantities in the table and find out the ratio. Do these ratios remain the same?
They are all 1: 16.
Keep the proportion unchanged
(3) What is the significance of the ratio in question (2)?
Significance: The loom will produce 1 hour16m.
(4) Are the two quantities in the table directly proportional? Why?
These two quantities are out of proportion because their units are different.
Judge whether two quantities in the following questions are directly proportional, and explain the reasons.
1. The height of the parallelogram is fixed, and its area is the same as the bottom.
Is S=a*h
2. The number of kilograms of apples per box is fixed, and the number of boxes and the total kilograms are fixed.
Yes, total = number of units * number of boxes.
3. A rectangle has a certain area, length and width.
No, S=a*b
4. The oil yield is certain, the number of kilograms of peanuts and the number of kilograms of oil squeezed out.
Is the number of kilograms of peanuts = oil quantity/oil yield.
5. The number of tickets and the amount paid for the same theater.
Is the total amount of money = ticket price * number of tickets.
6. The circumference and pi of a circle
It is not that pi is a fixed value, but that pi is proportional to circumference.
Fill in the blanks.
Output per hectare * number of hectares = (output value). When the output per hectare is constant, (output value) is inversely proportional to (number of hectares).
The numerator is definite, and the denominator is (inversely) proportional to the fractional value.
It is known that a and b are inversely proportional. Please complete the form below.
2 (8/3) and a half
Three and three quarters
Choose four composition ratio formulas from the divisor of 24 (1: 2 = 12: 24).
Questions and answers.
The computer factory assembles a batch of computers. The number of computers assembled every day and the number of days required are as follows.
The number of units assembled every day is 60 45 30 15 10.
Days required 3 4 6 12 18
1. What are the two quantities in the table? Are they related quantities?
The number of units assembled every day and the number of days required are related quantities.
2. Calculate the product of several groups of numbers of two quantities in the table. Do these products keep certain?
Keep the same, the values are 180.
3. What does the product in question 2 mean?
The products in the second question represent the total number of computers that need to be assembled in the computer factory.
4. Are the two quantities in the table inversely proportional? Why?
In inverse proportion.
Because their product is a constant value, how many times one quantity increases, how many times the other quantity decreases.