This kind of application problem is based on "planting trees". Any application problem of studying the four quantitative relations of total distance, plant distance, number of segments and number of plants is called tree planting problem.

The key to solving the problem: to solve the problem of planting trees, we must first judge the terrain and distinguish whether the graph is closed, so as to determine whether to plant trees along the line or along the perimeter, and then calculate according to the basic formula.

The rule of solving problems:

Planting trees along the line

Tree = total distance ÷ plant spacing+1

Tree = number of segments+1

Plant spacing = total distance present (tree-1)

Total distance = plant spacing × (tree-1)

Planting trees along the periphery

Tree = total distance ÷ plant distance

Tree = number of segments

Plant spacing = total distance.

Total distance = plant spacing × trees

There are 30/kloc-0 poles buried along the highway, and the distance between every two adjacent poles is 50 meters. Later, it was completely revised and only 20 1 was buried. Find the distance between two adjacent ones after modification.

Analysis: this question is to bury telephone poles along the line, and the number of telephone poles is reduced by one. The formula is 50× (301-1) ÷ (201-1) = 75 (m).

Second, the application of fractions and percentages.

1 Fraction addition and subtraction application problem:

Fractional addition and subtraction application problems and integer addition and subtraction application problems are basically the same in structure, quantitative relationship and solving method, but the difference is that there is a fraction in the known number or unknown number.

2 Fractional multiplication application problem:

Refers to the application of knowing a number and finding its score.

Features: The quantity and fraction of the unit "1" are known, and the actual quantity corresponding to the fraction is found.

The key to solving the problem is to accurately judge the number of units "1". Find the score corresponding to the required question, and then formulate it correctly according to the meaning of multiplying a number by a score.

3 fractional division application problem:

Find the fraction (or percentage) of one number to another.

Features: Knowing one number and another, find the fraction or percentage of one number. "One number" is a comparative quantity, and "another number" is a standard quantity. Find a fraction or percentage, that is, find their multiple relationship.

The key to solving the problem: start with the problem and find out who is regarded as the standard number, that is, who is regarded as "unit one" and who is the bonus compared with the number of unit one.

A is the fraction (percentage) of B: A is the comparative quantity and B is the standard quantity. Divide a by b ..

How much is A more (or less) than B (a few percent): A minus B is more (or less) or (a few percent) than B ... Relationship (A minus B)/B or (A minus B)/A.

Given the fraction (or percentage) of a number, find the number.

Features: Knowing an actual quantity and its corresponding fraction, find the quantity with the unit of "1".

The key to solve the problem is to accurately judge the number of units "1". Take the quantity of unit "1" as an equation of X according to the meaning of fractional multiplication, or as an equation according to the meaning of fractional division, but we must find out the known real corresponding to the fraction.

Quantity.

Third, measure

I. Length

What is length?

Length is a measure of one-dimensional space.

(2) Common length units

Kilometers (km), meters (m), decimeters (dm), centimeters (cm), millimeters (mm) and microns (um).

(3) Conversion between units

1mm = 1000 micron, 1cm = 10mm,1cm = 1m = 1000mm =

Second, the area

(1) What is the area?

Area is the size of the plane occupied by an object. The measurement of the surface of three-dimensional objects is generally called surface area.

(2) Public area unit

Square millimeter, square centimeter, square decimeter, square meter, square kilometer.

(3) conversion of area units

1 cm2 = 100 mm2， 1 mm2 = 100 cm2， 1 m2 = 100 mm2。

1 ha = 10000 m2, 1 km2 = 100 ha.

Third, quantity and quantity

(1) What are volume and volume?

Volume is the size of the space occupied by an object.

Volume, the volume of objects that can be accommodated in boxes, oil drums, warehouses, etc. , usually called their volume.

(2) Common units

1, unit of volume

Cubic meters, decimeters and centimeters

2. unit of volume: liters and milliliters.

(3) Unit conversion

(1) unit of volume

1 m3 = 1000 cubic decimeter

1 cubic decimeter = 1000 cubic centimeter

(2) unit of volume

1L = 1000ml

1 l = 1 m3

1 ml = 1 cm3

Fourth, quality.

What is quality?

Mass refers to the weight of an object.

(2) Common units

Ton: ton kg: kg g: g

(3) General conversion

One ton = 1000 kg

1 kg =1000g

Verb (short for verb) time

(1) What is time?

Refers to a period of time with a starting point and an ending point.

(2) Common units

Century, year, month, day, hour, minute and second.

(3) Unit conversion

1 century = 100 year

1 year =365 days (average year)

1 year =366 days (leap year)

One, three, five, seven, eight, ten and twelve are big months, and big months have 3 1 day.

Four, six, nine and eleven are abortions, and there are 30 days of abortions.

February in a normal year has 28 days and leap year has 29 days.

1 day = 24 hours

1 hour =60 minutes

1 min =60 seconds

Intransitive verb currency

(1) What is money?

Money is a special commodity, which acts as the equivalent of all commodities. Money is a general representative of value and can buy any other commodity.

(2) Common units

Yuan, Angle and Minute

(3) Unit conversion

1 yuan = 10 angle.

1 angle = 10 point