See if you can answer this classic brainteaser you might be asked in a Wall Street job interview

How would you answer?
When interviewing on Wall Street, job seekers often
come up against questions that could shock even the
most knowledgeable candidate.
This classic, however, has been asked so many times by
companies like Jefferies & Co. you'd be remiss not to
know how to approach this question:
"How many golf balls could fit on a 737 jet?"
The good news about brain-teasing questions,
according to Susan Sandler Brennan, executive director
of Career Services at Bentley University, is that they are
increasingly falling out of favor in the most competitive
banks, consulting companies, and tech firms.
"We found that brainteasers are a complete waste of
time. How many golf balls can you fit into an airplane?
How many gas stations in Manhattan? A complete waste
of time. They don't predict anything. They serve
primarily to make the interviewer feel smart," said
Google's SVP of people operations, Laszlo Bock, in a
New York Times interview .
But this isn't to say big companies don't still use
brainteaser interview questions, and candidates should
be prepared to encounter some riddles.
When asking this kind of question, interviewers are more
interested in seeing how you respond under pressure to
the shock of the question than the precise answer itself,
says Timothy Falcon Crack, a professor of Finance at
Otago University in New Zealand and author of " Heard
on The Street: Quantitative Questions from Wall Street
Job Interviews ."
And after the initial shock is over, he says they want to
see how you think about a quantitative problem that you
can't use "plain vanilla step-by-step algebra or calculus
to solve." These interviewers are looking for analysts
who can solve free-form problems that require
estimation and loose approximations, not rigid people.
When answering, Crack says you need to speak your
step-by-step logical reasoning out loud. "If you close
your mouth for 60 seconds and then declare the answer
is 10 million, I have no idea how you got to the answer,"
he says. "I don't actually care about the numerical
answer — assuming you are in the ballpark — I care only
about the demonstrated reasoning process."
You might answer this way:
So, let's start with how many people fit inside a 737.
Well, it varies, but 200 sounds about right. Each person
sits in a personal space about the size of a red British
phone booth. OK, the seat is narrower, but there are
aisles and overhead lockers etc., so it should be about
right. A golf ball must be about one inch in diameter. A
phone booth is about 36 inches wide, and let's say 75
inches high.
So, I get 36x36x75 balls in a booth, but let's simplify and
make it 30x30x100, that must be about the same, and I
can do it in my head more easily. So, I get 90,000 golf
balls in a phone booth. Then 200 phone booths in the
plane. 9x2 is 18 and I have to tag those six zeroes on
the end of it.
18 million is my answer, but maybe I will just round that
to 20 million because those balls are not cubes, and
they nestle in against each other more efficiently than do
little cubes.
Crack says there are, of course, other solution
techniques, but they all involve approximations and
some sort of estimation of relative volume.
Along the way he says he might have asked the
interviewer whether or not to include the cargo hold,
which would double the answer. "Ask the interviewer if
you are not sure of the assumptions," he says. "Maybe
they have specific assumptions in mind."
It might also be worthwhile to note that 20 million golf
balls are awfully heavy and the plane likely won't take
off with all those on board, he suggests.
"On one level, this is just a game," Crack says. "Beyond
skills, they also want to know whether you play well
with others. That's about fit or culture.
"Your reactions reveal your human nature. Your human
nature reveals whether you fit or not. If you make a clear
concerted effort, then it signals an interest in making an
effort more widely. And if you're willing to play along
and work hard for the answer, that signals the attitude
of someone who wants the job and is likely to accept it
if offered it."
How would you answer?