Rats and Anaesthesia Puzzle || Google Interview Puzzle
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- เผยแพร่เมื่อ 5 มิ.ย. 2024
- #SimplyLogical #InterviewPuzzle
Puzzle Details
In a Medical Laboratory, you have 240 Injections, one of which is for Anesthesia for a rat. If Anesthesia injection is injected in a rat, it will faint in exactly 24 hours. You have 5 rats available to determine which one injection contains the Anesthesia. How do you achieve this in 48 hours ?
according to this puzzle, you have 5 rats and 240 injections. Any small dosage of anaesthesia takes around 24 hours to be effective on a rat. Given the nature of anaesthesia, effectiveness refers to its tendency to make the rat faint. Thus any dosage of this anaesthesia should make them faint in approximately 24 hours. As the rest of 239 injections shows no effect, how will you find that particular injection which has anaesthesia in it using the 5 rats you have, within a period of 48 hours (2 days)?
this is an interesting logical puzzle asked in several job interviews.
Now take your time to arrive at a solution and watch the video for correct solution.
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Both answers are a bit flawed. The first answer assumes that you can inject 5 rats with 240 different injections within ... 0 secs otherwise you are outside of the time limit. The second method uses the information that the anesthesia works "in exactly 24 hours" as stated in the puzzle. (5 people can all inject the rats at the same time so we're within the time limit.)
A reasonable re-working of the problem would have the anesthesia working between 19 and 20 hours. This would nullify the second solutions, since you don't know exactly when the mouse would faint and would logically give a staff enough time to inject the mice (that is 300 injections per hour). Of course this solution would be incredibly wasteful, at least 1200 synergies thrown away in the name of science, but this is just a puzzle.
I went to straight to second, simpler method. Perhaps add a condition that the rats can only be injected at 24 hour intervals in order to get reliable results.
The written question clearly states in “exactly 24 hours”. So you only need one rat, the first solution was overly complicated.
Yeah, changed the rules part way through 😂
I dont know how prople dont like your first method, its is an amazing approach barring some meaningful assumptions. Google looks for such thinking patterns. Again great thinking for method 1.
Great visual explanation !!
I believe, I found a more optimal method.
You can identify the injection from 1024 injections in this method. (Therefore, obviously 240 is doable - however I’ll explain for 1024)
For day 1, divide the 1024 injections in 32 sets of 32.
Code each of the sets in 5 digit binary from 00000 to 11111. (For example, set 5 i.e 00101 is given to rats C and E, if only rats C and E lost movement, we know that the poison was from set 5)
Also note, the 32nd set is not given to any rat i.e is not rats lose consciousness the anaesthesia is in this set. This helps us determine which set the injection is from.
For day 2, repeat the process but instead of it being a set of 32 injections number each injection from 1 to 32 from the identified set.
I think it’s more optimum, because in your solution, we’re not getting the opportunity to inject the rats twice. In my proposed solution, we’re gaining information from all 5 rats on the first and then again on the second day.
The problem is that the video doesn’t say how long the anaesthesia effects. In another version of the puzzle, it’s killing the rat instead (which doesn’t allow to test a rat that got the lethal injection on the first day)
That won't work because you can't use the rat again after it got fainted ,so if say 4 rats fainted in 1st day you are now remaining with only 1 rat to test on the next day, and 32 injections left to test ,so won't be possible
Just Amazing!!
bahute badhiya sikhaye h guruji
well explained!
Nice explanation bro....
Nice!
what if we take one of the injection
What happens to the 3 injections left, if that has the anesthesia no rats faint
You have made the solution unnecessarily complicated.
1. Divide the injections in 5 batches of 48.
2. Map each batch to each of the 5 rats.
3. From each batch, inject the mapped rat at each half hour starting at 0 to 23 hours (48 injections).
4. Based on which rat faints, we'll know which batch has the bad injection. Based on at which hour the rat faints, you'll know which injection in that batch is bad
Q E D
this is given on gfg any other approach
i came up with the second soln by own bt as because of the given condition i thought this cant be the right way..
Thank you your video solved my confusion!
i came up with the second method qite quickly, pretty simple
Me : great explanation thanks. it's very helpful.
Random insta/twitter girl : this video should be banned , how dare you to do expirements on rats. If i do this experiment on you how would you feel
th-cam.com/video/3oFpncvCWnM/w-d-xo.html
Send this link to that girl.
It was originally on slave. 😅
It's simple : for each rat we have option to not inject , inject on 1st day or inject on 2nd day => this creates 3*3*3*3*3 = 243 ways and luckily we have 240 injections
So we inject all 5 rats with same injection again and again but with different pattern
Eg : 1 2 2 1 0 = rat1 injected on 1st day, rat2, rat3 on 2nd day, rat4 on 1st day, rat5 not injected
Let this be anethesia injection
After 1 day rat1, rat4 faints, after 2nd day rat2, rat3 faints and rat5 never faints .
This way we know which patterned injection is anethesia one
But we have to do task in 48 hours. So what if last injection which we injected is anethesia , so it would take more time than 48 hours , because we have to wait for 24 hours to see if rat is fainted or not after giving any 1 injection.
@@ujasdiyora2804 giving injection on 2nd day means start of 2nd day i.e after 24 hrs
First explanation is incorrect as well as lacks the minimum dosage criteria (if you say that in second solution 30 mins are less to check the effect). Further in 1st solution you are unnecessary complicating things just to show 5 digit code in the base of 3. As total outcomes will be 243(exactly 240) , that means each digit 0,1,2 effectively repeat itself in 243/3 = 81 ways that further means you have to inject lets say 1 st mouse of 1st solution 81 times on 1st day along with combination of 1s in the remaining 4 mouses. So injecting the first mouse 81 times in 24 hours means injecting it ifor subsequent testing n less than 18 minutes. Further in that duration, you have to inject the same injection to none, or/and second or/and third or/and fourth or/and fifth mouse to see the faint reaction of the injection as per the labelling. Hence second solution is the only correct solution in the above given solution and the remark to say that 30 minutes are too short to notice the reaction of injection are totally funny and shows lack of understanding of the solution in a similar manner that without landing gears a plane cannot fly....
why we gave second rat the same dose? when we can the results yes or no from the first rat after 24 hours?
Also levelling is not clear say you injected 10001 and 10201 on both Rat1 and Rat5 gets fainted after first 24 hour then you will again inject 10201 to verify ?
can you plzz give more examples of dry run?
you have valid doubt bro, see we will wait for 48 hour and then come to the conclusion hence 10001 and 10201 injection will have different effect.
the 1st and 5th rat will faint in cases of anesthesia injection and we might think 10001 and 10201 as our possible answer but after 48 hour we will able to confidently say which is our anesthesia injection.
I only need 1 rat.