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How many inches is a 54 cm TV equivalent to?
A 54 cm TV is a 21 inch one
1. Please use a 4.2-decimeter-long, 2.5-decimeter-wide rectangular cardboard to make a 0.5-decimeter-deep rectangular paperless carton (the thickness of the seams and cardboard is ignored, the larger the volume is, the better). How many square decimeters is the volume of the carton you made?
2. A rectangular glass fish tank, 4 decimeters long, 3 decimeters wide and 2 centimeters deep. There is water in the tank. The water surface is 2 cm away from the tank mouth. Now put a 7.5 kg stone into the tank. Will the water in the tank overflow? Why? (1 cubic meter stone weighs 2.5 tons)
3. A cuboid shaped water tank, measured from the inside, has a bottom area of 40.5 square decimeters. The height of the water surface in the water tank is 5.4 decimeters. There is a piece of marble weighing 63.18 kg in the water tank. When the marble is taken out of the water tank, what is the height of the water surface in the water tank? (1 cubic decimeter of marble weighs 2.6 tons)
1.
（4.2－0.5×2）×（2.5－0.5×2）×0.5
= 2.4 cubic decimeter
two
The volume without water is:
4 × 3 × (2 △ 10) = 2.4 cubic decimeter
The volume of the stone is:
7.5 △ 2.5 × 1000 △ 1000) = 3 cubic decimeters
3 cubic decimeter is greater than 2.4 cubic decimeter
So the water will overflow
three
40.5 × 5.4 = 218.7 cubic decimeter
The volume of marble is:
63.18 △ 2.6 = 24.3 cubic decimeter
(218.7-24.3) △ 40.5 = 4.8 decimeters
Practical problems in grade one of junior high school
1. The distance between a and B is 176 km, and one of them is blocked due to landslide. A and B engineering teams are instructed to set out from a and B at the same time at 8 am to dredge the road. At 10 am, team a arrived and started working immediately. Half an hour later, team B arrived and quickly put into "fighting" to work with team a, At this time, team a has completed 1 / 24 of the project
(1) If the length of the road damaged by the landslide is 1 km, the speed of team a is 3 / 2 times that of team B, which is more than 5 km. What is the speed of team a and team B?
(2) Assuming that the two teams finish the task of dredging the highway at 16:00 p.m., how long will it take if only team B dredges the highway?
2. "Beijing roast duck" not only requires delicacy, but also has many regulations. For example, the quality should also meet the standard. The following is the difference between the quality of two unprocessed ducks (unit: gram) and the standard quality. The number of less than the specified quality is marked as "-" and the number of more than the specified quality is marked as "+": - 50, - 60, + 20, - 20, + 200, + 75, + 50-125
(1) If the standard weight of each duck is 1000 grams, what is the average weight of the eight ducks?
(2) Which duck is better qualified and why?
3. Supermarket a and supermarket B sell the same goods at the same price. In order to attract customers, they launch different preferential schemes. After supermarket a has purchased more than 300 yuan, the excess part will be given a 20% discount on the original price. After supermarket B has purchased more than 200 yuan, the excess part will be given a 50% discount on the original price
Suppose that the customer's expected cumulative purchase cost is x (x > 300) yuan
(1) Please use the formula with X to represent the expenses paid by the customers in the two supermarkets?
(2) Li Ming is going to buy 500 yuan goods. Which supermarket do you think he should go to? Please explain why?
(3) How many yuan does Li Ming pay when he goes to two supermarkets?
1. (1) if the speed of team B is set at x km / h, the speed of team a is set at 3x / 2 + 5 km / h,
According to the meaning of the title, 2.5x + 2 * (3x / 2 + 5) = 176-1, we can get x = 30, 3x / 2 + 5 = 50,
So the speed of team a is 50 km / h, and that of team B is 30 km / h
(2) According to the meaning of the title, the speed of engineering team a is 1 × 1 / 24 △ 0.5 = 1 / 12 km / h. at 16 o'clock, the two teams finish the task of highway dredging, and there is a gap
(16-10.5) x + (16-10) × 1 / 12 = 1 can be solved, if only engineering team B dredges this section of highway, how long it takes t = 1 / x = 11 hours
2、（1）1000+（-50-60+20-20+200+75+50-125）/8=1011.25（g）
(2) The quality of ducks marked with + 20, - 20 was more suitable for the standard, because among the 8 ducks, the difference between their quality and the standard quality was the smallest
3. (1) supermarket a: 300 + (x-300) * 80% (yuan); supermarket B: 200 + (X-200) * 85% (yuan)
(2) If x = 500 is substituted into the two formulas in (1), supermarket a: 460 yuan; supermarket B: 455 yuan
Visible to B supermarket more preferential
(3) From 300 + (x-300) * 80% = 200 + (X-200) * 85% in (1), we get x = 600 (yuan),
It can be seen that when Li Ming bought 600 yuan goods, he paid the same fee to two supermarkets
How many cubic meters is 10 cubic centimeters
Ten to the minus fifth cubic meter
On the travel of solving application problems of the first series equations
Party A and Party B set out from a and B at the same time and walked towards each other. One hour later, they were 36 kilometers apart. After meeting, they continued to walk. When they walked for three hours, they were 36 kilometers apart. The distance between a and B was calculated
x+36=3*(x-36)
x=72
The distance between the two places is 72 km
25×64×125．
25×64×125=25×4×2×（8×125），=200×1000，=200000．
Let a = 1 + 3 + 5 +... + (2n-3) + (2n-1), where n is a natural number, and find the square root of A
The first two or more to include two
The summation formula of a sequence: (1 + 2n-1) * n / 2 gives a = n ^ 2,
That is, the square root of a is a
Urgent! Seventh grade mathematics midterm!
Seventh grade, but also with the answer!
Grade seven mathematics test time: 80 minutes Full Score: 120 points a multiple choice question (3 points for each question, 30 points in total) 1 stipulates that it is positive to walk northward, someone walks + 5 kilometers, someone continues to walk - 10 kilometers, then this person () a walks 15 kilometers northward, B walks 15 kilometers southward, C walks 5 kilometers northward, D walks 5 kilometers southward
2 out of 9 times 1 and 3 out of 8 equals 2 out of 27 times 3 and 3 out of 8?
11/36 1/4
He (she) is a landscape composition
It's about 700 words. Come on, first aid
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