Math problems to be explained, preferably explained .

I am a math teacher, the answers are absolutely accurate, and the later ones should not be plagiarized.

1.A 1/4 circle, its diameter is decimeters, and its area is ( ) square decimeters.

2.The total output value of a factory this year increased by 25% compared with last year, and last year's total output value was this year's ( )3There are 20 people present and 5 absent in a meeting, and the attendance rate is ( )20-5) 20*100%=75% choose d

4.The number A is 20% more than the number B, and the number B is the sum of two numbers ( ) The number B is 1 The number A is (1+20%) The sum of the two numbers is (1+20%+1) 1 (1+20%+1) = 5/11 Choose A

5.Two iron wires of the same length, welded into a square and a circle respectively, the comparison of their area size is ( ).

The circumference is equal, and the area of the circle is the largest

Multiply 2/5 + multiply 6 and 3/4 + 6 and 3/4 multiply 96 and 3/4 =

Application Questions:1Unit 1 is not divided by the same method, and the decrease from unit 1 is 1-8%368 (1-8%)=400 (yuan).

2.The ergonomics of A is 1 10, the ergonomics of B is 1 12, and the sum of the ergonomics of A, B, and C is (3 4) 3=1 4, so the ergonomics of C is 1 4-1 10-1 12=1 15

C alone for 1 (1 15) = 15 days.

The percentage of kilograms is 1 2-1 3 = 1 6

10 (1 2-1 3) = 60 kg.

4.The next day, I read 20 * (1 + 20%) = 24 pages.

A total of 44 pages were read in two days, and the corresponding score was 20% of the whole book

20+24) 20%=240 (page).

5.Radius: m).

Area: sq.m.).

square meters).

1: Diameter 2 to calculate the radius, and then divide the square of s=pai r by 4.

2: 100% divided by 125%.

3:20 divided by (20+5) multiplied by 100%.

4: 100% divided by (120%+100%)

5: The circumference is equal, and the area of the circle is the largest.

Application: 1:368 divided by (1-8%) unit 1 is not known by division, and the decrease from unit 1 is 1-8%.

2: The ergonomics of A is 1 10, the ergonomics of B is 1 12, and the sum of the ergonomics of A, B and C is 3/4 divided by 3=1 4, so the ergonomics of C is 1 4-1 10-1 12=1 15

It takes 15 days for C to do it alone.

3: 10 kg corresponds to a fraction of 1 2-1 3 = 1 610 divided by 1 6 = 60 kg.

4: The next day, I read 20 * (1 + 20%) = 24 pages.

A total of 44 pages were read in two days, and the corresponding score was 20% of the whole book

44 divided by 20%.

5: Find the radius by dividing the perimeter by dividing by 2.

Find the area by the radius.

Then divide by 8, these are the basic questions of the 6th grade of elementary school.

Won't do what shouldn't.

I am a 6th grade teacher.

Such a question should require a perfect score.

This is your teacher's question.

1) 10 4 + 5 4 + 3 4 = 72 (cm) 2) 10 5 2 + 10 3 2 + 5 3 2 = 190 (square centimeters) The sail width is dry before it.

A: At least 72 cm of clear iron wire and at least 190 square cm of paper are required.

Hope, thank you.

Ideas: This kind of question is mainly to grasp the common denominator, which here is the "total amount of work".

Topic analysis:1. A and B cooperate for 30 days to complete the "total amount of work".

2。A first does 12 days, then the two work together for 12 days, and the rest B has to do 16 days to complete the "total amount of work".

Conversion: Let A do x in one day, then B does (x+4) in one day, which is known from analysis 1.

The total amount of work is 30*(x+x+4).

It is known from analysis 2.

The total amount of work is 22*x+12*(x+x+4)+16*x, and the equation:

30*（x+x+4）=22*x+12*(x+x+4)+16*（x+4）

60x+120=62x+112

x = 4 B is 8

12+16)*8=224 (pcs).

It can be seen as their cooperation for 28 days.

1-1 30*28) (22-16) = 1 90 A day's workload.

B's workload in a day 1 30-1 90=2 90=1 45 There are a total of 4 (1 45-1 90)=360 B does a total of 360*1 45*(12+16)=224

4 [1 (16+12)x(1-(30-16-12) (22+12-30)]=224.

For your convenience, the first "1" represents the total number of parts that B did during the task, and the second "1" refers to the number of parts B does in a day.

1.Mr. Zhang deposited 10,000 yuan in the bank last year for a fixed period of one year. When it expires this year, he will receive 10,367 yuan after paying 20 yuan in interest tax. When Mr. Zhang saves money, the interest rate for a fixed year is ( ).

2.The processing of a batch of parts was originally planned to be completed in 25 days, that is, (4)% of these parts were actually completed in 20 days, that is, (5)% of the work efficiency (parts completed every day) of making this batch of parts every day was increased by (25)%.

3.The national law stipulates that if the monthly income of an individual's wages and salaries exceeds 2,000 yuan, the excess part shall be subject to individual income tax. Below is the standard of payment.

Tax payable for the whole month Tax rate.

The portion not exceeding $500 is 5% for the chain and 5%.

10% for the portion exceeding $500 to $2,000

15% for the part exceeding 2,000 yuan to 5,000 yuan

Question: Manager Zhang pays 125 yuan in taxes every month, so how much is his monthly salary? (Hint, think about what tax rate he applies?) ）

Forehead... The third question of calling the scum has not been calculated yet!! ~

I'm sorry!! ~

1,A (1-%20) A is 5a 4 A (1+%20) B is 5a 6

2. P=A-5A 4+A-5A 6=-A 12 A=80.

p=-80 12=-20 3 That is, the loss at this time is -20 30,000 yuan.

Minute solution: 1, let the distance be 1, then A's speed is 1 20, B's speed is 1 30, and A's journey takes x minutes to catch up with B.

Then (1 20) x 5 30 + (1 30) x solution gets: x 10

2.Suppose chickens eat feed x every day and ducks eat y every day

Then the total amount does not become: (9x+4y)12=(15x+20y)4 Simplification gets: 3x=2y

So the total amount of feed is (9x+4y)12=180x3 chickens and 10 ducks, eat 3x+10y=18x per day, so you can eat for 10 days. A

80 4 = 20 (yuan).

66 3 = 22 yuan.

27 4 = 6 ......3 people.

23 4 = 5 ......3 people.

6+1=7 rooms.

5+1=6 rooms.

6 80 + 66 + 5 80 + 66 = 1012 yuan.

Answer: Boys rent 6 rooms for 4 people, 1 room for 3 people, 5 rooms for girls for 4 rooms, 1 room for 3 people, a total of 1012 yuan.

There are 50 people in the class, 48 people rent a 4-person room, and 2 people rent a 3-person room.

1. The plan is reasonable: 5 quadruple rooms and 1 triple room for girls. There are 6 quadruple rooms and 1 triple room for boys.

150/75=2

Then there are other possible numbers 5=30, but 30 is not a multiple of 25, so it should be 50

So it's the last pot (red).

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In order to green the campus, the school placed three colors of chrysanthemums on both sides of the road from the gate to the teaching building in the order of 1 pot of white, 2 pots of yellow, and 3 pots of red, and the 66th pot of flowers was red.

66 (1+2+3)=11, 0 remainder

So, is the last pot of flowers in the color, red.

6 pots in a cycle, 66 6 = 11, then it is just the last one in the cycle, so it is red.