Ask for a math application problem, ask for a math application problem

Hehe is actually very simple, first of all, we have to assume that the earth is completely spherical, so the northern and southern hemispheres are the same!

Let the total area of the earth be 2, then the northern and southern hemispheres will be 1 each, and the land area of the earth will be a=2*41 (100+41)=

Northern Hemisphere land is b=1*65 (100+65)=Southern Hemisphere landmass: a-b=

The area of the Earth's oceans is c=2*100 (41+100)=Northern Hemisphere oceans d=1*100 (100+65)=So, Southern Hemisphere oceans c-d=

So the land area of the Southern Hemisphere is equivalent to the area of the ocean.

Solution: In order for all 45 students to arrive at the place of work as soon as possible, the 45 students should be divided into 3 groups, the first group will take the bus first, and then walk; The second group walks part of the distance (1 2 of the distance that should be walked) and then rides, and then walks the other part; The third group walked first and then rode in a car. In addition, these three groups of students set off from the school at the same time, and the distance by car and walk was equal, so that 45 students could reach the place of work at the same time.

The question tells us that the speed of the car is 60 kilometers per hour, and the speed of the students walking is per hour.

The first group took a bus to an underground bus, and the car immediately returned along the same road to pick up the second group of students. If the second group of students walked x kilometers at this time, then the car traveled 15 x kilometers. The first group of students went from school to drop-off.

It is known that the distance from the school to the place of labor is 30 kilometers, ie.

8x+2x=30

x=32x=6

That is, the walking distance is 6 kilometers, so the time taken to walk is.

6 4 = hours).

The distance by car is:

3 8 = 24 (km).

The time taken for the ride is:

24 60 = hours).

It is required at least to travel from school to the place of work. hours).

Let's set the equation: Let the total area of the earth's oceans be 1, then the land area is x, then the northern hemisphere ocean area is x, then the southern hemisphere ocean area is 1-x, the northern hemisphere land area is y, and the southern hemisphere land area is.

Known: x+y= (1-x)+(

y=Join, solve, and finally substitute (that's it.)

Let the land area x, the land area of the northern hemisphere y, then the land area of the southern hemisphere x-y and the ocean area are x and equal to y

There is x, there is y=65x 41

The percentage of the ocean in the Southern Hemisphere is p=(x-y) (x [x(1-65 41)] (x

That's how it works, but you're wrong.

Because it is impossible to have a total area ?!! smaller than the area of the Northern Hemisphere

If the price of each product is reduced by x yuan, then 2160 = (20-x) (100 + 10x) 2160 = 2000-100x + 200x-10x 2x 2-10x + 16 = 0

x-2)(x-8)=0

x=2 or x=8, that is, when the price is reduced by 2 yuan or 8 yuan, the profit is 2160

Set the price reduction of x yuan, you can make a profit of 2160 yuan per day, according to the meaning of the following equation: (100-x) * (100 + 10 * x) - 80 * (100 + 10 * x) = 2160, after solving the equation, it is obtained: x = 8 or x = 2, that is, when the price is reduced by 2 yuan or 8 yuan, the profit is 2160

Let the price reduction of each product be x yuan, 2160=(20-x)(100+10x)2160=2000-100x+200x-10x 2x 2-10x+16=0

x-2)(x-8)=0

x=2 or x=8 with a profit of 2160

50 500 = 25,000 yuan.

The price increased by one yuan, and the sales decreased by 10.

rose by n yuan, and sales decreased by 10n.

50+n）×（500-10n）

25000-500n+500n-10n²=25000-10n²

When n=0, this formula is maximum.

Therefore, the selling price should be 50 yuan, and the maximum profit = (50-40) 500 = 5000 yuan.

Multiply the two digits and its square is the largest, so when the unit price is 30 yuan, 300 can be sold. In this way, there is a square, and the maximum profit is 9000 yuan.

You know how to do it and you're not sure. The answer upstairs is clear.