你是SS Buoyant货船的船长 这是这艘船的处女航
You are the cargo director on the maiden voyage of the SS buoyant.
and you’ve agreed to transport several tanks containing
the last specimens of a critically endangered fish species
to their new aquarium.
Unfortunately, as you’re passing through shark-infested waters
该船遭遇风暴袭击 破坏严重 贵重货物全被抛入海里
the boat is battered by a fierce storm, throwing your precious cargo overboard.
And to make matters worse,
no one seems certain just how many fish tanks are missing.
Fortunately, you have a rescue sub at your disposal,
but only enough fuel for one trip to the ocean floor.
You need to know where the tanks are
so you can gather them all in one quick pass.
Not a single fish can be lost.
You decide to scan the three sectors of the ocean floor
where the cargo could have landed.
Thermal imaging shows 50 organisms in the area,
and you quickly realize that that number includes both your fish
the image for Sector Beta shows two tanks and four sharks,
and the image for Sector Gamma is blank.
Your sonar has malfunctioned,
and you’re going to have to go with the info you have.
You check the shipping notes,
but all you learn is that each tank had the same number of fish inside.
The cargo hold had space for anywhere from 1 to 13 total tanks.
but every sector will have at least one,
and no more than seven.
There’s no time to waste.
The tanks won’t withstand the pressure much longer.
As you descend in the sub, you review everything you know.
How many fish tanks do you need to find in Sector Gamma?
Hurry, the fate of an entire species depends on you.
Pause here if you want to figure it out for yourself.
Answer in: 3
Answer in: 2
Answer in: 1
let alone how many fish are in each one.
to compare multiple pieces of partial information – a table.
Since we know there are thirteen tanks at most,
and we already see six tanks in Sectors Alpha and Beta,
We also know that each sector has a different amount of sharks
with no more than seven in each one.
What about the number of endangered fish?
Out of the 50 total organisms in all three sectors,
we know at least seven are sharks,
leaving a maximum of 43 fish inside all the tanks.
And the more sharks we find in Sector 3, the fewer fish there are to save.
现在 所有水族箱内的鱼都是均等分布的 为什么这么重要呢？
Now, remember that the fish are equally distributed across all the tanks. Why is that important?
Because it means that one of the possible values for the total amount of fish
must be divisible by one of the possible values for the total amount of tanks.
看下表格 我们发现唯一一组有效的数据就是39条鱼可以被13个水族箱除尽 意味着每个水族箱箱3条鱼
And looking at the table, we can see that the only combination that works
With sharks swarming around,
you quickly pilot the sub through the first two sectors
before retrieving the remaining seven tanks in Sector Gamma.
You’ve saved the species and taken an impromptu dive.
你是SS Buoyant货船的船长 这是这艘船的处女航