Ask 6th grade math questions and explain why they do the same

In the sixth grade, there are 200 boys and 160 girls, and the number of boys is ()% of the number of girls

There are ()% more boys than girls

The number of female students is ()% lower than that of male students

2.The number A is 10 and the number B is 8Then the number of A is more than the number of B ()% and the number B is less than the number of A ()%.

3.The original price of a TV is 2000, and the current price is 1800The price of this TV has been reduced by ()%4.A school had 1,500 students last year and 1,650 this year, and the number of students this year is higher than last year's ().

A principle, analogous to ... The following is the number that is divided.

In the sixth grade, there are 200 boys and 160 girls, and the number of boys is (125)% of the number of girls and the number of girls is (80)% of the boys

There are more male students than female students (25)%.

The number of female students is lower than that of male students (20)%.

The number A is 10 and the number B is 8Then the number A is more than the number B (25)%, and the number B is less than the number A (20)%.

The original price of a TV is 2000, and the current price is 1800The price of this kind of TV has been reduced by (10)% A school had 1,500 students last year and 1,650 this year, and the number of students this year has increased compared with last year's number (10).

In the sixth grade, there are 200 boys and 160 girls, and the number of boys is the number of girls

200 160= Girl is the unit "1", use boy girl (teach you a method: front and back).

The number of girls is that of boys ().

160 200= Male is the unit "1", with female Male.

There are ()% more boys than girls

200-160) 160=25 The unit "1" for girls is the unit, and the number of male students is a few percent of that of the female students

The number of female students is ()% lower than that of male students

200-160) 200=20 The unit "1" for boys is a few percent of the number of boys than for girls, and the difference is used in the unit "1".

2.The number A is 10 and the number B is 8then the number of A is more than the number of B ().

10-8) 8=25 Number B is the unit "1", and the number A is a few percent of the number B more than the number B, and the difference number is used in the unit "1".

The number B is less than the number A ().

10-8) 10=20 The number A is the unit "1", and the number A is more than the number B is a few percent of the number A, and the difference is used in the unit "1".

3.The original price of a TV is 2000, and the current price is 1800The price of this TV has been reduced ().

2000-1800) 2000=10 The original price is the unit "1", and the price reduction is a few percent of the original price, and the difference is used in the unit "1".

4.A school had 1,500 students last year and 1,650 this year, and the number of students this year is higher than last year's ().

1650-1500) 1500=10 Last year's number of people was in the unit "1", and the increase was in the percentage of the previous year, using the difference in the unit "1".

If you don't understand, please ask! Satisfied!

Hey, here you go, it's not difficult, but it's troublesome to explain typing.

The other questions are of the same type

Summary. This is a fraction multiplication and division problem, first of all, we must find the quantity of unit 1 in the problem, and then solve it in a columnar way according to the amount of unit 1 fractions = fractions of the corresponding quantity. If the unit 1 is known, use multiplication, and if the unit 1 is unknown, use division, or answer the equation, and be sure to pay attention to the correspondence when solving fraction application questions, and figure out the correspondence between the fraction and the quantity.

Dear, what's the topic?

This one. The first question uses 100 + 100 1 5 to equal 120 kilograms, and the second question uses 80 1 3 = 240 people.

Good. This is a fraction multiplication and division problem, first of all, we must find the quantity of unit 1 in the problem, and then solve it in a columnar way according to the amount of unit 1 fractions = fractions of the corresponding quantity. If the unit 1 is known, use the multiplication hole to argue, the unit 1 is unknown, use the division, or the column equation to answer, the answer to the fraction application problem must also pay attention to the correspondence, to figure out the correspondence between the fraction and the quantity, of course, the hail can sometimes also convert the fraction into the number of parts, first find out how much a portion is, and then see how many copies are required to multiply a few on the line.

I'll come: If the landlord can't think of this question, then it must be that the positive proportion and the inverse proportion are not clear.

Definition of Positive Proportion and Inverse Proportionality:

Proportional: two related quantities, one quantity increases, because the quotient must be kept constant, so the other quantity has to increase with it, these two quantities are called proportional quantities, and their relationship is called proportional relationship

For example, if a b = c, if a x is to ensure that the quotient is constant, then b should also be multiplied by xIn this equation, a and b are proportional.

Inverse proportionality: two related quantities, one quantity increases, because to keep the quotient constant, the other quantity must decrease, these two quantities are called inversely proportional quantities, and their relationship is called inverse proportional relationship

For example, d b = e, if d x, to ensure that the product is constant, b should be divided by xIn this equation, a and b are inversely proportional.

Summary: In the same equation, the dividend is proportional to the divisor, and the two multipliers are inversely proportional.

Now let's get to the problem:

After calculation, we can come up with three formulas:

The number of square bricks The area of the square bricks = the area of the kitchen.

Then the number of bricks and the area of the bricks are the "two multipliers" in the "summary" above, so they are inversely proportional.

It's just a coincidence, because what is being asked here is the total number, that is, the total number is uncertain, let's look at the practice first.

Group A accounts for 4/15 of the total number of people, then the number of people in groups B and C accounts for 11/15 and the ratio of groups B and C is 6:5——— Bi Duan ———1) From this, the ratio of the number of people in groups A, B and C can be obtained: 4:

6:5 and then based on the fact that there are 16 more people in Group B than in Group A, it can be calculated that there are a total of 120 people.

The ratio of the three groups of people after (1) in your question is 6:5 just for the convenience of calculation, we can take a random ratio, such as 4:3

So how to calculate the ratio of the number of people in the three groups, here we know that the number of people in groups B and C accounts for 11/15, so divide 11 into (4+3) = 7 parts, each part is 11/7, B and C account for 7 respectively, so the ratio of the number of people in groups A, B and C is, 4:44 7:33 7, (the total number is 15).

Then let the total number be x, then x*(44 7-4) 15=16, and the solution is x=105, which means that it is not 6:5 that can be done, but it is a bit difficult for you in the sixth grade to change the ratio.

If the number of people in Group A is 4/15 of the total number of people, then the sum of the number of people in Group B and the number of people in Group C is 11/15 of the total number of people

Because the ratio of the number of people in group B to the number of people in group C is 6

The number of people in group B accounts for 6/15 of the total number of people in the sedan car, and the number of people in group C accounts for 5/15 of the total number of people in the closed car

Because there are 16 more people in Group B than in Group A.

So the total number of people is 16 (6 15-4 15) = 16 (2 15) = 120

A: A total of 120 people participated.

Solution: There are a total of x participants, the number of participants in Group A is 4x 15, the number of participants in Group B is (4x 15)+16, and the number of participants in Group C is 5 6 [(4x 15)+16]. A Yunxian calendar + B + C = total number of people. Pie leak.

4x 15+(4x 15)+16+5 6[(4x 15)+16]=xSide search: x=120 (person).

A: A total of 120 people participated.

regarded the giving to Houzhou as one copy, and then gave Houyi four copies of the slag. So each serving is 630 (1+4)=126. A was originally 126 (3 5) = 210, and B was 630-210 = 420

1, let the missing command 2 13 4 15 = 2 52 15 = 15 26 km. The distance between A and B is 15/26 of a kilometer. Search.

The bicycle travels 1/2/13 of a kilometer every 4 minutes, then it travels (2 13 4) kilometers in 1 minute and 15 (2 13 4) kilometers in 15 minutes.

2, (3 3 7-1) 2=(7-1) 2=12 minutes. It takes 12 minutes to finish sawing the log.

A 3-meter-long timber is sawed every 3/7 meters, that is, 3 meters of wood has several 3/7 meters, that is, 3 3 7, can be sawed 3 3 7-1 saw, and it takes 2 minutes to saw each saw, so it takes 2 minutes to see this wood for 2 minutes.

3. Set up X tons of sand in Pile A and 630-x tons of sand in Pile B.

2x/5+630-x=4（1-2/5）x

630-3/5x=4x-8x/5

630-x=4x

3x=630

x=210630-x=630-210=420

210 tons of sand in pile A and 420 tons of sand in pile B.

If you put 2/5 of the sand in pile A into team B, now pile B has 2x 5 + 360-x tons of sand, and pile A has sand (1-2 5) x tons, and now pile B has 4 times as much sand as pile A, so 2x 5 + 360-x = 4 (1-2 5) x.

1) The bicycle travels 2/13 km every 4 minutes. The speed of the excavation is 1/26 of a kilometer per minute. So the distance between the two places is 15/26 of a kilometer.

2) A piece of wood 3 meters long is sawn every 3/7 of a meter. A total of 7 sections can be sawn. So to saw 6 times. The duration is 12 minutes.

3) Set the armor with x tons. then B has 630-x tons. From the meaning of the question, it can be known that x=350

1.It turns out that there are x books on the lower floor.

3x+18-101=x+101

x=9292x3-18=258

It turned out that there were 258 books on the upper floor and 92 books on the lower floor.

2.Solution: Let the pinion rotate x revolutions per minute, and use the inverse ratio to solve 90x100=18x

x＝500500x5=2500

Pinion 5 min 2500 rpm.

1.Let the book on the lower level be x, then the book on the upper level is 3x+18 according to the meaning of the title 3x+18-101=x+101

Solution x=92

That is, the lower layer is 92 books, and the upper layer is 294

2.Set the wheel to rotate x per minute.

90:18=x:100 according to the title

Solution x=500

Therefore, the small ferry turns 5 times in 5 minutes and 5*500=2500 revolutions.

1. The ratio of the numbers A and B is 9:8, if B increases by 34, this is the quotient of the number A divided by the number of B is 10 7, and the number A is ()?

Solution: Let A be XThen:

x/(8/9x+34)=10/7

Solution: x=180

2.The average of the three numbers A, B, and C is 19, the ratio of A to B is 3:2, and the ratio of B to C is 3:2.

Solution: A: B = 3:2 = 9:6

B: propane = 3:2 = 6:4

So: A: B: C = 9:6:4

A = 3 * 19 * (9 9 + 6 + 4) = 3 * 9 = 27 B = 3 * 19 * 6 19 = 18

C = 3 * 19 * 4 19 = 12