Sixth grade Olympiad math masters come 7 questions .

1、b。This needs to be assumed one by one, and then substituted into what everyone says.

Is there a mistake in the 2nd question If there are two people, there will be a total of 7 people in the competition.

Field. Assuming that the winner of each win gets 1 point, and the loser does not score, then the total score = 6 games * 1 = 6, let the number of games won by A, B and C be x, D is y, 3x+y=6, x and y are integers, so y=0

km。Let the total length x, then (x 2-750) (x 40)=(x 2+750) (x 24), and calculate x=6000m

Sky. Let x be the number of days required for C, 8 (1 24 + 1 30) + 6 x = 1, and get x = 15

Sky. Let A, B and C each person do x, y, z per day, then 8 (x + y) = 9 (y + z) = 18 (x + z), this calculation is more complicated, the formula needs to be changed into three equations, x and y are represented by z, and then substituted into the third formula, 6z = x + y, then the speed of z is 1 6 of x + y velocity, so it takes 8 days * 6 = 48 days.

Sky. The conversion of this question is more complicated, with 6 questions, let x, y, z are three people do every day, so 5 (x + y) = 4 (y + z) = 6y + 2 (x + z), the same x, z with y to replace, get x + y = 4y, y speed is x + y speed 1 4, so it takes 20 days.

Didn't meet the target, D was right.

2.10 points for first place and 4 points for fourth place.

3.If A has only won 1 game, then D has won 2 games; If A wins 2 games, then Ding wins 0 games.

Rice. Sky. Sky. Sky.

Suppose there are 100 kilograms of apples, and the purchase price is 1 yuan kilogram.

The pricing is: 1 30% = yuan kilograms).

Sell: 100 70% = 70 (kg).

Left: 100 70 = 30 (kg).

Half of the list price is: = yuan kilograms).

The full purchase price is: 100 1 = 100 (yuan).

The actual selling price is: 70 = RMB).

The actual profit is: = RMB).

The actual profit margin that the store gets is: =

Set number: Apple weight 1000 kg, 10 yuan per kilogram. Cost: 10x1000=10000 (yuan).

Priced at 30% profit margin, pricing: 10x(1+30%)=13 yuan to sell 70%, sell: 1000x70%=700 (kg) sold: 13x700=9100 yuan.

The rest is all sold at half the list price.

Left: 1000-700 = 300 kg.

Half of the price: 13 2 = yuan.

The rest sold: yuan.

A total of sold: 9100 + 1950 = 11050 yuan The actual profit margin of the store is: (11050-10000) 10000x100%=

After selling 70%, the total amount of the order money that has been recovered is:

Then the remaining 30% will be based on the ** of the price, and then the money will be recovered

So the total sales are: 91%+

Hence the profit is.

If the original price is 1, then the first 70% of the selling price is 1*(1+30%)=, and then the selling price of 1-70%=30% is.

So, average selling price = 70%*

So, the actual profit margin = (

Actual profit margin.

Let the cost price be x, then:

The selling price is x+x*30% = 130%*x, and the selling price is 130%*x *70% +130%*x *30% *= 130%*x*(70%+15%)

130%*x*(85%)

The profit is = =

Set the cost of this batch of apples to 1* is the multiplication sign 1* (1+.)

A batch of rice was stored in two grain depots, and the amount of rice stored in warehouse A was 2 3 that of warehouse B, and later 45 tons were transported to warehouse A and 36 tons to warehouse B, and the weight of rice in the two grain depots was equal. How many tons of rice was originally in Jiaku?

Warehouse A turned out to be less than warehouse B: 45 36 9 (tons).

Original: 9 (1 2 3) 27 (tons).

A warehouse original: 27 2 3 18 (tons).

Answer: The original 18 tons of rice in Jiaku.

The difference between the grain stored in warehouse A and warehouse B is 45-36 = 9 tons, the original warehouse B is 9 (1-2 3) = 27 tons, and the original warehouse A is 27 2 3 = 18 tons.

It's simple. I am also in the sixth grade, and I often do this kind of question: from the amount of rice stored in the first bank is 2 3 of the second store, it can be seen that there are 3 parts of the second store, and 2 copies of the first store, so if they are equal, you have to transport one copy to the first store, but now it is 45 tons to the first store, and 36 tons to the second store, then use 45 minus 36, which is equal to 9, indicating that one part is 9, and then just use 9 times 2 (don't multiply by 3, because what is sought is the original) can be.

Of course, I used the number of copies.

Equation: 45 36 9 (tons) 9 2 18 (tons).