1. A ballpoint pen
(1) What are the two related quantities in the table?
(2) Tell the ratio of two corresponding numbers in several groups of these two quantities.
(3) What does each set of equations explain?
(4) Are the two related quantities proportional? What proportion?
2. Among the three quantities of distance, time and speed:
(1) What is the ratio of time to distance when the speed is constant?
(2) When time is fixed, what is the ratio of distance to speed?
(3) When the distance is constant, what is the ratio of speed to time?
3. A rectangle has a certain area, length and width.
4. build a road, the number of meters repaired and the number of meters left.
Second, understand the following proportions.
1.2.3.3. List the proportions according to the following conditions and solution proportions.
The ratio of 1.5 and 8 is equal to the ratio of 40 and x.
2. The ratio of sum is equal to the ratio of sum.
3. The ratio of the left end of the equal sign is 1.5∶x, and the ratio of the right end of the equal sign is 3.6 and 4.8 respectively.
Answer:
First, judge whether the following questions are proportional. What proportion?
1.
2.( 1) When the speed is constant, time and distance are directly proportional.
(2) When time is constant, distance is directly proportional to speed.
(3) When the distance is constant, speed and time are inversely proportional.
3. A rectangle has a certain area, and its length and width are inversely proportional.
4. build a road, and the number of meters repaired can't compare with the remaining meters.