Till 15 Flashcards
You and 9 other individuals are captured by aliens. They choose to let you guys go if you pass a test.
The test goes as follows: You’ll be placed in height order and each of you will be given a cap - black or white in color. You will have to guess the color of your cap. If 9 out of 10 get it right, all of you will be spared. What strategy will you follow?
The tallest man can see 9 ppl in front of him. If there are odd number of black caps, he says black otherwise he says white. This man has 50% probability of getting it right.
Say he says black, now the person in front of him knows that there are odd number of black caps before the last person. Now they count the number of black caps that r visible. If it turns out to be even, then the person can understand that they have a black cap. This goes on until the last person gets it right.
4 ppl are stuck with zombies. You can cross the bridge in a minute, B can cross in 2mins, C needs 5, D needs 10. Zombies will catch over in 17 mins.
Bridge can take only 2 ppl. And lantern is must to cross. The lantern can light only a small amount of space. What strategy to save everyone?
Key is to minimise time the time wasted by letting the two slow ones go together. Next u
First, U and A cross which takes 2mins. Now 15 left. U come back with lantern. 14 left. Let C and D cross, 4 mins left. Now ask B to bring lantern. 2mins left. Now both of u cross. So u reach there in remaining 2 mins.
100 prisoners story. They can approach the guard and ask him to let them out. If they have green eyes, they ll be set free, otherwise burnt.
1 saver is let in and they can make a single statement. What will the saver say such that he does not disappoint the king and also saves all 100 prisoners?
Atleast one of you has green eyes.
Reason:
First see the case of 2 ppl, on day1 they see each others eye and assume their eye is red. cus the other one’s eye is green. but the next day, the other person does not escape. Which means that he too has seen green eye. So the ppl become aware that they have green eyes and escape.
In the case of 3, they look at each other. And one sees two green eyed ppl. Say 3 assumes he has non green eyes on the first day, 1 and 2 were just seeing each other and so will leave. But next day also they r there. Which means that 3 also has green eyes and so on for all others.
You have two fight against -
1] Sorceror Niz that can turn ppl into fish but only works 70% of the times
2] Sorceror Leib that can turn ppl into statue but only works 90% of the times
Lots are drawn and u go first, then Niz, then Leib
U have 3 wands - 60%, 80%, 100%
So what do you use to increase ur winning chance.
Say I choose 100% wand and Leib. Leib will be turned, but now Niz will kill you.
Say I choose 80% wand and Leib, if shes killed il be killed as well.
Say I choose 80% wand and Niz, if he killed il be killed as well.
Say u missed the shot, now Niz will kill Leib. Ul have 80% chance of wining. But there is another chance of Niz missing the shot. Now when it goes to the Leib, she knows u r more powerful cuz 80>70 and will kill you. This wudnt have happened with the 60% shot. So u choose 60 and miss. If Niz hits or misses, Leib will still kill him cuz he more dangerous and so You will get the next chance and u can WIN.
There are two baskets of 5 apples each. Green basket apples have 2 dangerous ones, whereas the red one has 3 dangerous ones. If u choose green, ul have to eat 3 apples at random. If u choose Red ul have to eat 2.
If 1 danger apple - ul be saved. If two dangered apples, u die. Which basket dyu use.
You and ur team crash landed an alien planet. The only way off is to appease its 3 alien lords - tee, eff, arr. By giving thm the crct artifacts. U dont know who is who. Frm inscription, u may ask 3 yes or no qns. each to any 1 lord. tee’s always true, effs always false, arrs random. U can ask the qn in their lang, but they ll reply with, Ozo or ulu, u dnt know which is yes and which is no among this. How to still figure out which alien is which.
Your research team finds a prehistoric virus and isolates for study. At night due to power cut, samples broken. The virus is contained for now, but unless u can destroy it. the vents can open and unleash a plague. U grab ur HazMat suit nd get ready to save the world. Lab is a 4*4 compound of 16 rooms. w entrance at NW corner and exit at SE. Each room cnctd to other. And virus released in every room except entrance. To destroy, u must pull its switch. Once u enter contaminated room, u cannot exit without activating the switch. And once u do so ul not be able to go back in. How to destroy every room virus
Hamiltonian path problem. NP-Complete. hamiltonian path say on chess board. start on black will hav to end on white. nd even sided grids - opposite corners are same colors. si start frm 1 to end on opp not possible.
CATCH: entrance room is not contaminated. so can use that again. so say u destroy the right room and come back to entrance. now goto below room and ul have four paths to clear. Otherwise go to the second room first and again ul hav 4 paths.
Your rich eccentric uncle jst passed away. U and 99 nasty rels have been invited to fulfill his will. He wanted to give all his money to u. But ur rels will pester u he knew. He knows u know to solve puzzle.
He created puzzle if all 100 solve then it shd be shared. If only 1 finds, they get it.
A secret room w 100 locker each hiding a single word. Ever rel assigned 1 number.
Heir 1 will open every locker. Heir 2 will close every 2nd locker. Heir 3 will change the status of every 3rd and so on.
The words that remain open in the end will help u crack code,
U immediately understand which lockers will rem open by the end. But how
Square numbered lockers will open.
cuz num of times locker touched = num of factors.
opened lockers = odd factors = square nums like 1,4,9,…so on.
Code turns out to be “The first 5 lockers touched only twice”
That means first 5 primes.
ANS: 235711
Ur fav band keeps misplacing instruments on tour. It drives manager mad.
On concert day, band wakes up to find themselves tied in a windowless soundproof practice room.
There are 10 mislabelled boxes outside with instruments. every1 gets to open 5 boxes. and ul hav to identify which box has ur instru. how dyu inc ur winning chane.
Start by taking a box labelled ur instru. if diff instru shows up, go to next box pointing that keep gooing till u d=find urs. This has 35% better chance of passing thru. as in in a loop with less than 5 objs ur object will be thr.
further expln in doc
Ur expedition stands at the ancient temple. Thrs a danger. There are 5 hallways, including 1 to altar and rem 4 outside. 60 mins left. 20 mins to reach exit. 2 students wer cursed. 1 or both m8 lie. u dnt knw which student cursed. U only know one thing for sure and that is u are not possessed.
u can chk 3 out of 4 rooms to find the escape. cuz if first 3 rnt, we know the 4th is right. uk tht ul not lie, so u can take 1 path alone, rem 8 send 4 to each door. if two possessed together, other room set will give same answer, and u find the truth. if possessed not together then only 1 will lie and u can find the way out.
BUT TRHS A CATCH IN TWO POSSESSED TOGETHER CASE, THE 4th ROOM M* BE ANS
Actual sln
u alone, 2 , 3, 3
Code of 3 numbers, wach number is whole positive. 2nd num>=3rd and 3rd num>= 2nd.
she may ask for upto 3 clues.
xyz=36
x+y+z=same as num of hallway she entered. zara knows the number of that hall but we dont.
Clue3 Largest number appears only once in the combi.
also note that she need 3 clues to escape despit being perfect logician
Last point means that thr wer two or more combos of first 2 clues. so zara was confused nd asked for 3rd clue
ANS 229
One of his 12 governors paid w counterfeit coin. The coins are together. Thrs a counter balance and marker. U may use it only 3 times. The fake coin must be heavier or lighter
Split in 4s. Chk any 2 set of 4s, if equal,mark em 0. Next take three 0 coins with 3 frm rem set , if they balance, the left out one is fake, otherwise. if not draw on the three coins. and take 2 and weigh and conclude.
if first itslf no balance, mark as +,-. replace 3 coins in - side with 0s and 3 coins in + side with -. Now if heavier side is still heavy, + or - on either side is culprit. choose any 1 of this and measure with a + or - respectively . ul get ans
U eat a poisonous mushroom. Male and female frogs look identical.Female secretions can save ur life. Male has a unique croak. U spot a frog. But on the other side u hear a croak and see 2 frogs, and dnt know which croaked. what are better chances of clearing, if u go to either side. u can lick two frogs together also
one frog dirn, prob is 50%
in the other dirn, we hav only possibilities due to croak, MF,FM,MM. Amd 2 of 3 is chance of survival. 67%
