BI picked up on these questions in March. Most are from IBankingfaq.

See how will you answer those.

#### 2. Three envelopes are presented in front of you by an interviewer. One contains a job offer, the other two contain rejection letters. You pick one of the envelopes. The interviewer then shows you the contents of one of the other envelopes, which is a rejection letter. The interviewer now gives you the opportunity to switch envelope choices. Should you switch?

http://www.ibankingfaq.com/interviewing-brainteasers/three-envelopes-are-presented-in-front-of-you-by-an-interviewer-one-contains-a-job-offer-the-other-two-contain-rejection-letters/

#### 3. A windowless room has 3 light bulbs...

You are outside the room with 3 switches, each controlling one of the light bulbs. If you can only enter the room one time, how can you determine which switch controls which light bulb?

#### 7. You are given 12 balls and a scale. Of the 12 balls, 11 are identical and 1 weighs EITHER slightly more or less. How do you find the ball that is different using the scale only three times AND tell if it is heavier or lighter than the others?

And more...at BI

8. During a visit to a mental asylum, a visitor asked the Director what the criteria is that defines if a patient should be institutionalized.

"Well, said the Director, we fill up a bathtub. Then we offer a teaspoon, a teacup, and a bucket to the patient and ask the patient to empty the bathtub."

1. Would you use the spoon?
2. Would you use the teacup?
3. Would you use the bucket?

"Oh, I understand," said the visitor. "A normal person would choose the bucket, as it is larger than the spoon."

What was the director's response? (author: easterbaby 2003)

9. You are locked inside a car and have a bat. How do you get out without breaking a window ?

10. Brad stared through the dirty soot-smeared window on the 22nd floor of the office tower. Overcome with depression he slid the window open and jumped through it. It was a sheer drop outside the building to the ground. Miraculously after he landed he was completely unhurt. Since there was nothing to cushion his fall or slow his descent, how could he have survived the fall?

8. You just pull the plug in the bathtub. (This is a brainteaser?)

9. If you're locked inside just unlock the car's doorhandle locks. (Once again, this is a brainteaser or am I reading this wrong?)

10. He is a window cleaner. (I had to google this one :) ).

hopingtobreakin:

8. You just pull the plug in the bathtub. (This is a brainteaser?)

9. If you're locked inside just unlock the car's doorhandle locks. (Once again, this is a brainteaser or am I reading this wrong?)

10. He is a window cleaner. (I had to google this one :) ).

Right. Let me ask you this now,

How can you eat a bucket full of ice cream in less than 5 minutes (or so) with only a teaspoon at your disposal ?

Winners bring a bigger bag than you do. I have a degree in meritocracy.

Financier4Hire:

hopingtobreakin:

8. You just pull the plug in the bathtub. (This is a brainteaser?)
9. If you're locked inside just unlock the car's doorhandle locks. (Once again, this is a brainteaser or am I reading this wrong?)
10. He is a window cleaner. (I had to google this one :) ).

Right. Let me ask you this now,

How can you eat a bucket full of ice cream in less than 5 minutes (or so) with only a teaspoon at your disposal ?

Assuming you can eat a bucket full of ice cream, you could just use your hands. Or if you're being nifty here reflect sunlight or any other form of light on the ice cream, it will melt and you can drink it.

Do you have 5 minutes from beginning to end or just 5 minutes from the point you start.

Financier4Hire:

hopingtobreakin:

8. You just pull the plug in the bathtub. (This is a brainteaser?)
9. If you're locked inside just unlock the car's doorhandle locks. (Once again, this is a brainteaser or am I reading this wrong?)
10. He is a window cleaner. (I had to google this one :) ).

Right. Let me ask you this now,

How can you eat a bucket full of ice cream in less than 5 minutes (or so) with only a teaspoon at your disposal ?

Wait for the ice cream to melt, then drink up in 5 minutes.

2) No, because originally you have a 33.33% chance of getting the offer, once you see one of the envelopes, you now have a 66.66% chance of getting the offer and a 33.33% chance of getting the other rejection, you do not switch. variable change

3) It doesn't say the switches are attached to a wall or anything, so just take the 3 switches with you into the room.

5) 60 mph?

lrs2050:

2) No, because originally you have a 33.33% chance of getting the offer, once you see one of the envelopes, you now have a 66.66% chance of getting the offer and a 33.33% chance of getting the other rejection, you do not switch. variable change

3) It doesn't say the switches are attached to a wall or anything, so just take the 3 switches with you into the room.

5) 60 mph?

5) It's not possible unless you can warp from one place to another instantly. You already traveled 60 miles over 2 hours (30 mph). You can't average 60 mph for the entire trip.

lrs2050:

2) No, because originally you have a 33.33% chance of getting the offer, once you see one of the envelopes, you now have a 66.66% chance of getting the offer and a 33.33% chance of getting the other rejection, you do not switch. variable change

3) It doesn't say the switches are attached to a wall or anything, so just take the 3 switches with you into the room.

5) 60 mph?

u should switch:

3 Envelopes. 2 Reject and 1 Job

1) You pick Reject A.
-You are shown the second Reject.
-You switch and you get the Job.

2) You pick Reject B.
-Identical scenario

3) You pick Job.
-You are shown a Reject.
-You switch and you get rejected.

So switching means you win 2/3rds of the time. This is because in no scenario are you shown the Job envelope.

thankyoucomeagain:

lrs2050:

2) No, because originally you have a 33.33% chance of getting the offer, once you see one of the envelopes, you now have a 66.66% chance of getting the offer and a 33.33% chance of getting the other rejection, you do not switch. variable change
3) It doesn't say the switches are attached to a wall or anything, so just take the 3 switches with you into the room.
5) 60 mph?

u should switch:

3 Envelopes. 2 Reject and 1 Job

1) You pick Reject A.
-You are shown the second Reject.
-You switch and you get the Job.

2) You pick Reject B.
-Identical scenario

3) You pick Job.
-You are shown a Reject.
-You switch and you get rejected.

So switching means you win 2/3rds of the time. This is because in no scenario are you shown the Job envelope.

it depends on if the interviewer knows what's in the envelope

6)
Initially you'd think to just divide it by 2 three times, but eventually you'll reach 3 balls which won't be able to divide evenly.

The only way to do it is to get some power of 2. So you separate the 12 balls into separate powers of which are 2^3 and 2^2, 8 and 4.

You can divide the 8 again by 2 and get 4.

So just weigh 2 sets of the 4 balls and if they're equal then that means the other set has the heavier ball, and if they're not equal then you know which set has the heavier ball. Divide that set again and measure, and then divide the remaining set of 2 to get the heavier ball.

BigTalkinWalker:

6)
Initially you'd think to just divide it by 2 three times, but eventually you'll reach 3 balls which won't be able to divide evenly.

The only way to do it is to get some power of 2. So you separate the 12 balls into separate powers of which are 2^3 and 2^2, 8 and 4.

You can divide the 8 again by 2 and get 4.

So just weigh 2 sets of the 4 balls and if they're equal then that means the other set has the heavier ball, and if they're not equal then you know which set has the heavier ball. Divide that set again and measure, and then divide the remaining set of 2 to get the heavier ball.

You take 6 and 6, and set aside the heavier group.

Measure the group you set aside. Then do 3 and 3, again set aside the heavier group.

Use the group you just set aside. Now measure 1 and 1 (with one on the side). If they are equal, the heavier ball is the one on the side. If not equal, you pick the heavier 1.

no need to go into that deep of math

I eat success for breakfast...with skim milk

Financier4Hire:

BI picked up on these questions in March. Most are from IBankingfaq.

See how will you answer those.

5. A car travels a distance of 60 miles at an average speed of 30 mph. How fast would the car have to travel the same 60 mile distance home to average 60 mph over the entire trip?

.

I like this question: "How do you value the hot dog stand at Union Square in New York City?

If you're attempt a DCF on this nutty case, what are your assumptions.

Yes @ hopingtobreakin:

reflect sunlight or any other form of light on the ice cream, it will melt and you can drink it.
Winners bring a bigger bag than you do. I have a degree in meritocracy.

Lads, lads, lads... you always switch the envelope. See the Monty Hall problem here. (Don't discount because it's wikipedia).

http://en.wikipedia.org/wiki/Monty_Hall_problem