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Google Job interview!

Bilal [PersonRank 10]

Wednesday, March 19, 2008
11 years ago6,394 views

desihotmasala.com/2008/01/craz ...

some questions from Google job interview.

1. How many golf balls can fit in a school bus?

2. You are shrunk to the height of a nickel and your mass is proportionally reduced so as to maintain your original density. You are then thrown into an empty glass blender. The blades will start moving in 60 seconds. What do you do?

3. How much should you charge to wash all the windows in Seattle?

4. How would you find out if a machine's stack grows up or down in memory?

5. Explain a database in three sentences to your eight-year-old nephew.

6. How many times a day does a clock's hands overlap?

7. You have to get from point A to point B. You don't know if you can get there. What would you do?

8. Imagine you have a closet full of shirts. It's very hard to find a shirt. So what can you do to organize your shirts for easy retrieval?

9. Every man in a village of 100 married couples has cheated on his wife. Every wife in the village instantly knows when a man other than her husband has cheated, but does not know when her own husband has. The village has a law that does not allow for adultery. Any wife who can prove that her husband is unfaithful must kill him that very day. The women of the village would never disobey this law. One day, the queen of the village visits and announces that at least one husband has been unfaithful. What happens?

10. In a country in which people only want boys, every family continues to have children until they have a boy. if they have a girl, they have another child. if they have a boy, they stop. what is the proportion of boys to girls in the country?

11. If the probability of observing a car in 30 minutes on a highway is 0.95, what is the probability of observing a car in 10 minutes (assuming constant default probability)?

12. If you look at a clock and the time is 3:15, what is the angle between the hour and the minute hands? (The answer to this is not zero!)

13. Four people need to cross a rickety rope bridge to get back to their camp at night. Unfortunately, they only have one flashlight and it only has enough light left for seventeen minutes. The bridge is too dangerous to cross without a flashlight, and it’s only strong enough to support two people at any given time. Each of the campers walks at a different speed. One can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and the slow poke takes 10 minutes to cross. How do the campers make it across in 17 minutes?

14. You are at a party with a friend and 10 people are present including you and the friend. your friend makes you a wager that for every person you find that has the same birthday as you, you get $1; for every person he finds that does not have the same birthday as you, he gets $2. would you accept the wager?

15. How many piano tuners are there in the entire world?

16. You have eight balls all of the same size. 7 of them weigh the same, and one of them weighs slightly more. How can you find the ball that is heavier by using a balance and only two weighings?

17. You have five pirates, ranked from 5 to 1 in descending order. The top pirate has the right to propose how 100 gold coins should be divided among them. But the others get to vote on his plan, and if fewer than half agree with him, he gets killed. How should he allocate the gold in order to maximize his share but live to enjoy it?

You merit a job at Google if you can answer one of these ...

Mrrix32 [PersonRank 10]

11 years ago #

There goes my dream then :-)

6. 23?
7. Find a Map (Google Maps?)

I could guess at the others but no where near sure about them :D

David Mulder [PersonRank 10]

11 years ago #

Whether they are true or not I love these questions and I had an answer ready for nearly all of them :P

1. I would need a comuter for this one, but if I would be give some time I could do it.
2. If you lie down, the blades shouldn't hit you
3. Its impossible to wash all windows in Seatle so why even think about charging money for something you can't finish.
4. -
5. A really big hall with toys and hunderds of robots which will get a toy if you describe it to them :P
6. 23...
7. Check the internet
8. Or I would throw away all my shirts or I would change my music mashup into a shirt mashup in google mashups
9. – This question makes no sense
10. Very well, incorrectly assuming that there is a 50%-50% chance that would mean that 1:2 would be a girl... this answer first seemed irlogical to me, but greatslovakia.com/tmp/stupidgi ...

I will probably finish this list later...

PS. My spelling is probably even worse as usual, cause I am tired and sick...

Bilal [PersonRank 10]

11 years ago #

>Mrrix32
6- 23 : yes sure
7- I don't think this is the best answer

>David Mulder
10- then it can be easily computed E(x)= 0.5 x 1+ .... x 2 + ... x 3 + ...

David Mulder [PersonRank 10]

11 years ago #

[put at-character here]Bilal: What would you suggest then for 7...

Tony Ruscoe [PersonRank 10]

11 years ago #

7: Try anyway...?

Bilal [PersonRank 10]

11 years ago #

[put at-character here]David Mulder:
I will do a search centered in A using an optimization algorithm.

Colin Colehour [PersonRank 10]

11 years ago #

I remember seeing some of these a couple of years ago:
gamedev.net/community/forums/t ...

Bilal [PersonRank 10]

11 years ago #

[put at-character here]Tony Ruscoe
7: Try anyway...?

may be, some questions have exact answers like :
1,17,16, 12,6,10

but
7 or 15!!!

Philipp Lenssen [PersonRank 10]

11 years ago #

> 1. How many golf balls can fit in a school bus?

The answer is "1". One golf ball can fit in a school bus. Of course, more than that can fit too, so this isn't the only correct answer.

> 2. You are shrunk to the height of a nickel and your mass
> is proportionally reduced so as to maintain your original density.
> You are then thrown into an empty glass blender. The blades
> will start moving in 60 seconds. What do you do?

Tell the dude who threw me in the blender that his wife is cheating on him, and that I will reveal more if only he stops the machine and helps me out.

> 5. Explain a database in three sentences to your
> eight-year-old nephew.

"Jimmy, you remember the MySQL InnoDB thingie you set up last week for your sister's school homepage? Well, that was a database..."

> 7. You have to get from point A to point B. You don't know
> if you can get there. What would you do?

If I'm still the height of a nickel I would kindly ask the dude who previously put me in the blender to please carry me on his hands, to him it's a short distance. And then I'd try get my own TV show as smallest man on earth...

Bilal [PersonRank 10]

11 years ago #

[put at-character here]Philipp Lenssen

For the database you get it, for the rest i am not sure.

Rohit Srivastwa [PersonRank 10]

11 years ago #

Philipp
You are hired :)

Rohit Srivastwa [PersonRank 10]

11 years ago #

for me most of the answers are same

"I'd Google it."

Mrrix32 [PersonRank 10]

11 years ago #

12. 7.5 degrees (the hour hand has moved a quarter of the way between 3 and 4)

Roger Browne [PersonRank 10]

11 years ago #

> 16. You have eight balls all of the same size. 7 of them
> weigh the same, and one of them weighs slightly more.
> How can you find the ball that is heavier by using a
> balance and only two weighings?

I can do better than that.

I can start with nine balls all of the same size. 8 of them weight the same, and one of them weights slightly more.

I load the balance with three balls on one side, three on the other, and three not on the balance. This tells me which group of three contains the heavier ball.

Then I load the balance with one ball on one side, one on the other, and one not on the balance. This tells me which ball is the heaviest.

Bilal [PersonRank 10]

11 years ago #

[put at-character here]Mrrix32:
i agree, it is exactly 7.5 degrees

[put at-character here]Roger Browne
Yes but it more confusing with 8, because with 8 one will first think to split into 4 + 4. which will require three weighings

MarWi [PersonRank 3]

11 years ago #

17: The allocation is 5:99 4:0 3:1 2:0 1:1 (5 being the highest ranked)

The game has to be solved backwards:

If there were only two pirates, the higher ranking would take it all.

If there are 3 pirates, the highest ranking pirate would know that in the next round the lowest ranking pirate would get nothing, so he offers him 1.

If 4 pirates are in the game, the highest ranking knows that in the next round the seconds lowest would get nothing, so the distribution would be 4:99 3:0 2:1 1:0

Now, with 5 pirates, the highest ranking can make sure to get the two supporting votes by giving number 3 and number 1 each one coin as they stand to lose if he's out of the game.

MarWi [PersonRank 3]

11 years ago #

10: The answer is 50% – 50%. – (incorrectly) assuming chances for a having a boy are equal to having a girl...

Anyone got an answer to Nr9?

Either one or all of them. Every woman knows that 99 men are cheating. Then the queen comes along and says 1 man is cheating. As long as no man is getting killed, this proves that your man must be cheating (otherwise some woman would kill hers)...as soon as one man dies we are back at the point where every woman thinks only all the other men cheat. However, you could also say that all men die as the women will abide by the law and kill their husband at the exact same time, namely the last second of the very day.

MarWi [PersonRank 3]

11 years ago #

3: 100$ per hour

Roger Browne [PersonRank 10]

11 years ago #

[put at-character here]MarWi: I think number 9 is straightforward, but there are two cases.

If we are sure that the queen is honest, then 99 of the women will know that some other husband cheated. So if a woman does not know that another husband cheated, then she must kill her own husband.

On the other hand, if there is a possibility that the queen is not telling the truth, then no woman can have enough certainty to kill her husband.

Ionut Alex. Chitu [PersonRank 10]

11 years ago #

10. The number of failures (to have a boy) follows a geometric distribution whose expected value is 1/p (p=0.5, the probability of having a girl), so you need two trials before getting one success.

Bilal [PersonRank 10]

11 years ago #

[put at-character here]MarWi
3: 100$ per hour

This is a good answer, i didn't get this

[put at-character here]Ionut Alex. Chitu
10. then the expected value E(x) = 1/p = 2, which is the needed answer here

G [PersonRank 1]

11 years ago #

seoptimization.blog.com/251447 ...

More questions and anecdotes

David Hetfield [PersonRank 10]

11 years ago #

As Martin said, there goes my dream :P

DPic [PersonRank 10]

11 years ago #

Ooh! These look fun :) I'm going to make it a point to solve as many as i can without looking here except to see if someone else has solved it already.

[put at-character here]Roger for #16: you could probably figure this out if you haven't already but to do it with 8 balls you do something similar to what you said for 9. Put 3 balls on each side. If it is even then you weight the two that weren't weighed. If one side is heavier you weigh two and leave out one and that will give you the answer.

This is very similar to a problem i had to solve earlier this year in math (well, i didn't have to, i just happened to be the first one who did). A king has many golden statues made of himself but one of the people making them is stealing gold and making the statues less pure. His statues weight less. Given one statue from each of the makers, what is the quickest way to find the statue which weighs less, given a scale (not a balance) and weighing them all at once without weighing any of them more than once? Let me know if that needs clarification

Bilal [PersonRank 10]

11 years ago #

[put at-character here]DPic

So the number of the makers is not important
if i knew how much the bad status are lighter (lets see x)

i will take
1 status from the first maker
2 from the second
3 from the 3rd
...

n from the nth

the if i find 5 x missing then it is the 5th maker

or i didn't understand well

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