There are 7 bottles of pop-up beverage, one of which is less in quality. If you weigh it with a balance at least several times, you can find the bottle with less in quality

There are 7 bottles of pop-up beverage, one of which is less in quality. If you weigh it with a balance at least several times, you can find the bottle with less in quality

Two times. Take any one out, and the other six will be randomly divided into two groups. If the balance is balanced, take out that one is less. If the balance is tilted, one of the three on the other side will not be heavy enough. Weigh any two in the group again, and the defective product can be selected in the same way

A supermarket sells one kind of beverage. It can sell 100 cases per day on average, and the profit is 120 yuan per case. If the price of each case is reduced by 1 yuan, it can sell 2 more cases per day
Under the condition that the profit of each box of drinks is more than 80 yuan, in order to make the daily sales of drinks profit 14400 yuan, how much yuan should be reduced per box?

Let X be reduced, then the system of equations is established
120-x greater than or equal to 80
（100+2x）（120—x）=14400
The solution is enough~

In order to meet the national day, the supermarket decided to adopt appropriate price reduction measures to expand sales, increase profits and reduce inventory. According to the market survey, if the price of each box of milk is reduced by 0.4 yuan, then an average of 8 more boxes can be sold every day The daily profit is 120 yuan. How much is the average price reduction per carton of milk?

Let's reduce the price of each carton by X Yuan. According to the meaning of the question, we get (4-x) (20 + x0.4 × 8) = 120. The solution is X1 = 1, X2 = 2. In order to expand the sales volume, X1 = 1 is not satisfactory. Let's omit x = 2. Answer: the average price of each carton of milk is 2 yuan

The ratio of the number of sold bottles to the number of unsold bottles is 1:3. If another 150 bottles are sold, how many bottles are there?
When a supermarket sells drinks, the ratio of the number of sold bottles to the number of unsold bottles is 1:3. If another 150 bottles are sold, the ratio of the number of sold bottles to the number of unsold bottles is 2:3?

Set the total amount of beverage as X:
1/4X+150=2/5X
Go to the denominator
5X+3000=8X
X=1000
That is, the original beverage has 1000 bottles