The volume formula of the ball is the volume of the ball = four-thirds * π * radius of the third power. Two small iron balls with a radius of 5.2cm are melted and multiplied by a large iron ball. It is known that the mass of iron per cubic centimeter is 7.8G, and there is 1% loss in the molten iron. The mass of the molten large iron ball is calculated (π is 3.14, the result is accurate to 1g)

The volume formula of the ball is the volume of the ball = four-thirds * π * radius of the third power. Two small iron balls with a radius of 5.2cm are melted and multiplied by a large iron ball. It is known that the mass of iron per cubic centimeter is 7.8G, and there is 1% loss in the molten iron. The mass of the molten large iron ball is calculated (π is 3.14, the result is accurate to 1g)

The third power of 7.8 × 2 × 3 / 4 × 3.14 × 5.2 × 99% ≈ 5114 (g)

A company deals in two kinds of goods, one is 120000 yuan for each kind of goods, the other is 145000 yuan for each kind of goods. The other is 80000 yuan for each kind of goods, the other is 100000 yuan for each kind of goods, and their purchase price and selling price remain unchanged. Now we are going to buy 20 kinds of goods, the capital used is not less than 1.9 million yuan, not more than 2 million yuan. (1) what kinds of purchase plans does the company have? (2) Wang, manager of the company, said, "if you follow the purchase plans in (1), you can make a profit of 445000 yuan at most after sales." is his statement correct? Try to explain after calculation

(1) According to the meaning of the title: 12x + 8 (20 − x) ≤ 20012x + 8 (20 − x) ≥ 190, the solution: 7.5 ≤ x ≤ 10, because x is an integer, so x = 8, 9, 10, there are three purchase schemes: scheme 1: a 8, B 12; scheme 2: a 9, B 11; scheme 3: a 10, B 10. (2) conclusion: the company's Wang The manager's statement is incorrect. The reason is: the profit of scheme 1 is: 8 × (14.5-12) + (20-8) × (10-8) = 440000 yuan; the profit of scheme 2 is: 9 × (14.5-12) + (20-9) × (10-8) = 445000 yuan; the profit of scheme 3 is: 10 × (14.5-12) + (20-10) × (10-8) = 450000 yuan. Therefore, the maximum profit of the company after selling according to the above three schemes is 450000 yuan Manager Wang's statement is wrong

Difficult, urgent (10 21:21:18)
The weight of a piece of gold silver alloy is 250 grams, which is reduced by 16 grams in water. The weight of gold in water is reduced by 19 percent, and that of silver is reduced by 10 percent

Let the mass of gold and silver be x and Y respectively
x+y=250;
x*(1/19)+y*(1/10)=16;
The solution is: x = 190, y = 60

First day mathematics rational number, please answer in detail, thank you! (29 17:1:4)
1+2+22+23+...+299+2100=
(detailed)

1+2+2^2+2^3+...+2^99+2^100
?
According to the summation formula Sn = A1 (1-Q ^ n) / (1-Q) = (a1-an * q) / (1-Q)
1+2+2^2+2^3+...+2^99+2^100=2^101-1