Interesting Interview Questions

Few questions that I found interesting from Google interviews which aren’t supposed to get right answer but to test the IQ of candidate. So here are the questions and various answers.


Question: 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?


A: If you are shrunk K times, the force you can exert with your muscles, which is approximately proportional to the cross-section of your muscles, decreases K2 times, and the length (path) on which you exert this force decreases K times. Hence the energy your muscles can deliver decreases about K3 times, which is just enough to jump in the same height as before, because your mass also decreases K3 times. This is just a rough estimate, but “hypothetically” you could surely jump out of a 15-20 cm high glass blender.


B: Take off all my clothes, wedge them between the blades and the floor to prevent it from turning. Back up against the edge of the blender until the electric motor overheats and burns out. Using the notches etched in the side for measuring, climb out. If there are no such notches or they’re too far apart, retrieve clothes and make a rope to hurl myself out.


C: I quickly realize that even if I get out, I am only the size of a nickel, and will probably never get laid again, so I place my neck on the blade and close my eyes till my 60 seconds are up.


D: You’re the height of a nickel, the blades won’t touch you on any blender I’ve ever seen. So sit back and ponder a solution at your leisure, there’s really no rush.


E: If your height was halved you’d only need one fourth the muscle power (take a look at small animals, they all have relatively much smaller limbs than larger ones). If you were reduced to the height of a nickel you would not only be able to lift many times your own weight, your body would quite possibly tear itself apart.


F: Go down to the base of the blades and duck. Mixer blades in blenders normally have a gap underneath them, and in some blenders, the blades are curved. You could survive for a long time crouched down there. With your fingers in your ears.


G: Since your density is the same, you weigh much, much less. Being that small means that the wind pressures created in the blender will toss you into the blades, so just sitting and pondering will get you nowhere except dead.


H: If you’re the height of a nickel and you’re thrown into a blender, you would be killed when you are thrown into glass blender.


I: First, I would be pissed that I was the height of a nickel. Second, I would commit suicide.


J: Move (swim) to the middle. The blades of the blender will generate a vortex/whirlpool, of which the calmest portion is the center – where there are also no blades.


K: I’d get out. (Interesting 🙂 )




Question: “How would you find out if a machine’s stack grows up or down in memory?”


A: Instantiate a local variable. Call another function with a local. Look at the address of that function and then compare. If the function’s local is higher, the stack grows away from address location 0; if the function’s local is lower, the stack grows towards address location 0. (If they’re the same, you did something wrong!)


B: You declare two data segments and assign them to the same address, then instantiate local variables in each of them and compare their addresses.


C: In a function, declare 2 local variables. Compare addresses.


D: The last time I programmed in Assembler was 1979.



Question: “Explain a database in three sentences to your eight-year-old nephew.”

A: A database is a way of organizing information. It’s like a genie who knows where every toy in your room is. Instead of hunting for certain toys yourself and searching the whole room, you can ask the genie to find all your toy soldiers, or only X-Men action figures, or only race cars — anything you want.


D: A database is like a pack of Top Trumps in its plastic box. Instead of Gumball Cars, Fast Boats or other Top Trumps stuff, you can make up your own deck. You can then do all kinds of Top Trump like things, comparing cards and stuff like that.




Question: “How many gas stations would you say there are in the United States?”


A: A business doesn’t stick around for long unless it makes a profit. Let’s assume that all gas stations in the US are making at least some profit over the long run. Assume that the number of people who own more than one car is negligibly small relative to the total American population. Figure that 20% of people are too young to drive a car, another 10% can’t drive because of disability or old age, 5% of people use public transportation or carpool, another 5% choose not to drive, and another 5% of the cars are inventory sitting in lots or warehouses that a dealership owns but which no one drives.


There’s about 280 million people in the US; subtracting 50%, that means there’s about 140 million automobiles and 140 million drivers for them. The busiest city or interstate gas stations probably get a customer pulling in about twice a minute, or about 120 customers per hour; a slower gas station out in an agrarian area probably sees a customer once every 10 or 15 minutes, or about 4 customers per hour. Let’s take a weighted average and suppose there’s about one customer every 90 seconds, or about 40 customers an hour. Figuring a fourteen-hour business day (staying open from 7 AM to 9 PM), that’s about 560 customers a day.


If the average gas station services 560 customers a day, then there are 250,000 gas stations in the US. This number slightly overstates the true number of gas stations because some people are serviced by more than one gas station. [Actual number in 2003, according to the Journal of Petroleum Marketing: 237,284, an error of about 5%.]


C: There are too many gas stations and too many cars in the country.

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