# Numerical logic question - interview practice

I don't know where to pu this question so I'm putting it under C# and .Net.

I have another interview on Friday and I was told there will be numerical logic whatever testing on a whiteboard. Ugh. I'm seriously thinking about saying I won't do it but of course I can't. Not that interested in the position so I might end up saying it. Why so some companies put the candidate thru the grinder?!

Anyway, I'm practcing some questions. Is the answer to this question 12?

How old is Jane ... if in 38 yrs... she will be 3 times as old as she is today?
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IT ManagerCommented:
How old is Jane = x

x + 38 = 3x
x - 3x = -38
-2x = -38
x = 19

Double check,

how old is Jane (19) in 38 years (19 + 39 = 57) = 3 times older than now (3 x 19 = 57)

It's basic math. Shows how analytic you are, even if you never had math. Analytic minds can solve problems they never encountered before. It means, you can solve problems you didn't learn for, by using other traits than just learning the material beforehand. Some people focus on what they've learned, and can only accomplish tasks within that realm.
Some people didn't learn anything, but can accomplish tasks in almost  ANY realm, because of their analytic minds.
It's kind of (but not exactly) as the saying goes, “You give a poor man a fish and you feed him for a day. You teach him to fish and you give him an occupation that will feed him for a lifetime", the first being someone taught specific material, and he only knows this material, nothing more, and the second being an analytic mind (can do anything without actually having learnt it)

Hence, do well in these tests, and yes, you do deserve the upper hand over other candidates.

In your case, you had an answer, which you didn't even bother to double check (using the same logic as I did above, not using math, just using language and common sense). Even if you didn't solve it with math, it wouldn't be too much to ask you to reason backwards if 12 was correct or not. Because someone without any math background would still get the correct answer quite fast (reasoning 12 wasn't correct, probably trying 15, ending up with 19 in no time). You will always get the answer with an analytic mind, the math only gets you there faster because you use a structured proven way to solve it. You tried neither though.

As you described the interview, it seems like it will be a creative and challenging job, using the mind freely to get to solutions. I'm pretty positive help desk positions where you read a script like a mindless automaton (where customers can pick this up within seconds, and hate the call already, because it probably won't help them to the solution, only keeping them trapped and looped inside the script) don't do these tests. That fact alone should entice any interviewee in my opinion (unless you actually wanted that mindless helpdesk job)

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IT / Software Engineering ConsultantCommented:
I'm probably biased being a Math major myself, but I strongly believe having good skills with math, numbers, logic and analytical problem solving is critical to programming.  At least as important as knowing the mechanics and syntax of the language.  And I think it's easier to learn a new language than to learn how to think analytically, and puzzle out number problems.

And to be fair, that question you posed is a pretty basic math / problem solving, so if they ask something like that I don't think that's unreasonable, they're just trying to make sure some minimum ability exists that they think is important.

»bp
Commented:
Commented:
Another way to look at it is if you add 38 to her age that makes her three times her current age, so 38 must be twice her current age.
\Commented:
>> How old is Jane = x
>> x + 38 = 3x

If this is for a programming position interview, I recommend that you modify the whiteboard wordings to include units. And emphasize how important units are. Look up mars landing crash and Hubble telescope units mismatch and mention those two. Also when you are given a word problem, then a good way to start is to break the problem down using words rather than trying to jump right into equations. This way you get a chance to think and talk about the problem and collect your thoughts, and the interviewer gets a chance to hear your thought process.

``````Suppose Jane is x years old.
In 38 years, Jane's future age will be (x+38) years old.

This future age is 3 times her current age; that is,
Future age = 3 × current age
(x+38) = 3 x
``````
Even if you don't know how to do the math, if you can just show your thinking, you will get lots of partial credit. I know this from experience.
Author Commented:
thanks guys. I'm mentally exhausted at work with my manager's moody and abusive behavior (those of you who've been helping me know my situation)...who knows I came up with 12...

Let me step back , collect my thoughts and read the answers. I need to focus, I know.
CIOCommented:
Seems like you need a new job.
Don't accept moody and abusive behaviour, and - in general - avoid bad managers.

You reached 12, I guess, by guessing. That won't do in programming where the devil is in every detail.
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