Who has math 6th grade little expert answer 20

47. Think: When No. 1 and No. 2 depart at the same time the next time, the time elapsed must be both a multiple of 12 minutes and a multiple of 18 points. That is, their least common multiple.

Solution: The least common multiple of 12 and 18 is 36

6 hours + 36 minutes = 6 hours 36 minutes.

A: The next simultaneous departure time is 6:36 a.m.

48. Think: The difference between the age of the father and the son is (45-15) years, and when the age of the father is 11 times the age of the son, this difference is exactly (11-1) times the age of the son, so that we can find out how old the son is, and the father is 11 times the age of the son. I also know that my son is 15 years old this year, and the difference between the two ages is the problem I wanted.

Solution: (45-15) (11-1) = 3 (years).

15-3=12 (years).

A: 12 years ago, the father was 11 times the age of the son.

49. Think: According to the meaning of the question, the conditions in the question can be transformed into: the average score is given to 2 students, 3 students, 4 students, and 5 students are all one less, so the least common multiple found and then subtract 1 is the problem of requirements.

The least common multiple of the solution is 60

60-1=59 (branches).

A: There are at least 59 pencils in this box.

50. Think: According to only increasing the bottom by 8 meters, the area will increase by 40 square meters, and the height of the original parallelogram can be found. By increasing the height by only 5 meters, the area will increase by 40 square meters, and the base of the original parallelogram can be found.

Multiply the original base by the original height to get the required area.

Solution: (40 5) (40 8) = 40 (square meters).

A: The original area of the parallelogram was 40 square meters.

The Paradise of Knowledge on page 10.

Please send out the question, thank you.

Hello: Girth. 10x2+

Meter area 10x6 = 60 square meters.

Your adoption is what keeps me going

If there are new questions, please ask me for help, it is not easy to answer the questions, please understand o(o, remember to praise and adopt, help each other.

Good luck with your studies!

Circumference 32m

The area is 10 by 6 60m squared.

Perimeter = 2*10 + 6 (

Area=6*10=60 Idea: Move the left semicircle to the right.

The first page is (6) (

12) (8) (relative) (phase.

Right) (6) (square) (8) (12) (same) (front) (back) (5) (up) (down) (left) (right) (9) (5) (8) (4) (right) (false) (right) 60 divided by 12 times 5 equals 25 square centimeters.

4) (2) (3) (36) (24) I sometimes send it later, and then I just say (it's okay).

The total number of students in the two classes is: 2 10 50 = 1000 people.

99989 1000 = 99 (this) ......989 (Ben).

On average, each person can get 99 copies, and there are 989 left.

2.Solution: Set x turns.

60x=100x120

x=12000/60

x=yuan)60 (1-20%)=75 (yuan).

t) 270-81 = 189 (t).

189x4 9 = 84 (tons).

5.(517 (car).)

proportional. y-2x=0

y=2xy/x=2

The third question is lost, and the cost of children's shoes is calculated in 118 months. Question 5: The formula for the cylinder used in this child's shoes, multiply 1 3 less. Additional question: It decreases with the increase of x, so it is not proportional.

Large square: circle: small square = 4: : 2 looks

Large square: Small square = 2:1

Draw a "ten" in the middle of a large square to easily see it.

The diameter of the bottom surface of the cylinder is 2 times the radius of the bottom surface;

The side area of the cylinder = the height of the bottom perimeter.

The base area of the cylinder = the square of the radius.

Surface area of the cylinder = side area + 2 base area.

It's okay to bring in the formula. Is it okay to be so lazy?

If the length is x steps, then the width is x - 12 steps.

So there is x(x-12)=864

x²-12x-864=0

x=36 (x=-24 rounded).

So 36 steps long and 24 steps wide.

A and B will set off at the same time.

Move it to make two circles, and the big circle can be obtained by decreasing the circle.

The shaded area can be expressed as a large circle - a small circle ==27 4