Problem Solving - Estimate the Number of Golf Balls
- 03:17
Investment Banking Superday interview problem solving - Can you calculate how many golf balls would fit in a classroom?
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Other ones that you might get on a problem solving area.
Um, so you might get, so we might wanna have a slightly more, uh, stretching question here that, um, maybe how many golf balls could you find? Could you fit into a classroom? Okay. I actually, look, I really like these questions.
I found quite fun to work out.
Did you say it was how many golf balls? In a, in a something? In a, In a classroom.
Oh, in a classroom. Okay. Brilliant. Okay.
I I do actually enjoy these questions. Okay, great. So there's a couple things we have to think about. First, couple parameters.
Firstly the size of a golf ball and the size of the classroom.
'cause ultimately we're gonna be working out the, the size of the classroom divided by the amount the size of the golf balls is gonna give us the amount of the golf balls.
Yep. So a typical classroom tends to have about 20, 25, maybe even 30 chairs in it.
And we can use that as a sort of benchmark.
'cause each chair and desk will have maybe a three, uh, maybe, uh, a two by two meter radius.
So if we expand that out, we'll probably get to a 40, maybe 40 meters by 40 meters is a bit much, uh, maybe that's slightly overestimating it and an actual desk and chair being close to, to one and a half meters.
So the estimate I'm gonna go with the classroom is, is, um, 90 meters squared, 30 by 30.
I think a square is a nice, makes it quite helpful for us with the maths.
Yeah. Could, could also be a rectangle, but we'll go over a square and then we need to think about a golf ball.
And the annoying thing about the golf ball is that it's, it's, it's circular.
It's spherical. So in reality there's gonna be a lot of leftover space, but that's okay.
So I don't play golf, but I know that a golf ball is around maybe the size of a closed fist.
So I'm gonna estimate that that is maybe half a, maybe oh 0.2 meters wide, nor 0.2 meters tall.
So in terms of volume, ah, that's the other thing we didn't think about in the classroom.
The height as well. The, so the height's gonna be, let's say two meters for simplicity.
Yeah. So that's actually gonna be 180 meters cubed. And volume is important. Now the golf ball, although I've measured it's two meters tall and two meters wide, we need to think about as it, as a square fitting into a square.
So it's probably, this is, this is much more detail I normally go into, but let's say that the golf ball is north 0.3 meters wide, north 0.3 meters, uh, width, not 0.3 meters height.
So 0.3 cubed is gonna be point.
Okay, so north 0.3 square is north 0.9 and no. Okay, let's go. Okay, let's say it's n 0.9 meters cubed.
Now we then need to divide 180 meters cube divided by N 0.9, which is gonna be, well, 180 divided by nine is uh, two, uh, is 20, add another zero.
So 200. And then, because it's law 0.9, 'cause actually in reality it's not north 0.9, it's north point nor nine, it's gonna be a couple hundred os after that.
So it's gonna be about 20,000 if I've got that right Now that is a crazy number and that's a crazy calculation.
But I hope that's, that there's some good thought process along the way.