x+x/3+x/9+x/27 & gt； =47
27x/27+9x/27+3x/27+x/27 >=47
(27+9x+3x+x)/27 & gt； =47
(27+ 13x)/27 & gt； =47
27+ 13x >= 1269
13x >= 1242
x & gt= 1242/ 13
x & gt=95.53846 153846 153846 153846 1538462
This problem cannot be calculated by an equation or a formula, but it has a logical process, as follows:
Since the minimum exchangeable unit is 1 bottle, the calculation starts from 1:
1*3=3*3=9*3=27
You can't take the exam again, or you'll pass 47.
Now we know that if we buy 27 bottles, we can get 27+9+3+ 1=40 bottles, leaving an empty bottle.
So there are still 47-40=7 people who haven't got coke, which means they can get another 7 bottles. Continue:
1*3=3
You can't take the exam again, or you'll pass 7.
Now we know that if you buy 3 bottles, you can actually get 3+ 1=4 bottles, leaving an empty bottle.
So there are still 7-4=3 people who haven't got coke, that is, just take three more bottles. Continue:
Because there were two empty bottles before, it would be good to buy two more bottles. In this case:
There are still 3-2= 1 people who didn't drink coke, and there are two empty bottles left this time.
Add the first four empty bottles, and then change to 1 bottle of new coke to meet the demand of the remaining bottle.
There were only two empty bottles left in the end.
Add up the quantity purchased before: 27+3+2=32 bottles, and the final answer is.
Verification:
Buy 32 bottles, the remaining 47-32= 15 people didn't drink, and the remaining 32 bottles were empty.
Replace 30 empty bottles with 2 empty bottles = 10 bottles of new coke, 15- 10=5 people didn't drink, 10+2= 12 empty bottles.
Replace it with 12 empty bottles =4 new cokes, leaving 5-4= 1 people not drinking, leaving 4 empty bottles.
Three empty bottles = 1 bottle of new coke, everyone drank it, leaving 1+ 1=2 empty bottles.
So 32 is the final correct answer.
Note: This logical method can be used to convert any number of people and any empty bottle into coke.