Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2006-03-08 14:33:13

kkkkk
Guest

i need help with this math problem

3 eyed martians met with earthlings (each with 2 eyes) in the first ever intergalactic. observers noticed that there were only 14 people, yet there were 34 eyes. how many of the people are earthlings?

#2 2006-03-08 15:20:28

Ricky
Moderator
Registered: 2005-12-04
Posts: 3,791

Re: i need help with this math problem

Here's the way I did it, a very non-matimatical way.

Let's assume that everyone is human.  Then there are 28 eyes.  For every human we replace with a martian, the net gain is 1 eye.

We need to gain 34-28 = 6 eyes, meaning there are 6 martians.  Thus, there are 8 humans.


"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

Offline

#3 2006-03-08 17:09:31

Dionysus
Member
Registered: 2006-03-06
Posts: 9

Re: i need help with this math problem

Or you could do it the mathmatical way:

3x + 2y = 34        (3 eyes for each martian, 2 for each human, is equal to 34)
x + y = 14            (martians and humans combine to 14 people total)

we need to solve for y, ill choose the second equation and get:
y=-x + 14

Now substitue that in for y in the first equation and simplify:
3x + 2(-x + 14) = 34
3x - 2x + 28 = 34
x = 6

Now since X stands for martians, we know we have 6 martians, leaving us with 8 humans.
If you plug those in for the first equation you will find 3(6) + 2(8) = 34, thus there are:

6 Martians (18 eyes) and 8 (16 eyes) Humans.

Last edited by Dionysus (2006-03-08 17:10:25)

Offline

#4 2006-03-08 17:58:26

Ricky
Moderator
Registered: 2005-12-04
Posts: 3,791

Re: i need help with this math problem

My way took about 5 seconds tongue

But I also had a feeling kkkkk didn't know how to solve systems of equations yet.  But I see no other mathimatical way to do it.


"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

Offline

#5 2006-03-08 18:48:38

ganesh
Moderator
Registered: 2005-06-28
Posts: 21,298

Re: i need help with this math problem

3m+2e=34
m+e=14--->2m+2e=28
Therefore, m=6, e=8.
No. of maritans=6, no. of earthlings=8.
(Time taken = about 15 seconds)

This is how I teach my students to approach problems involving Simultaneous equations. Most examinations give about half a minute or less to solve such problems, and I think this is the best way it can be done!

dizzy roflol up


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

Offline

#6 2006-03-11 23:55:16

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: i need help with this math problem

Ricky wrote:

Here's the way I did it, a very non-matimatical way.

Let's assume that everyone is human.  Then there are 28 eyes.  For every human we replace with a martian, the net gain is 1 eye.

We need to gain 34-28 = 6 eyes, meaning there are 6 martians.  Thus, there are 8 humans.

That's not very non-mathematical. It's logical at least, and logic fits in very micely with maths.
It's just a bit unconventional. It's how I'd have done it, though.


Why did the vector cross the road?
It wanted to be normal.

Offline

#7 2006-03-12 02:02:10

damathgirl
Member
Registered: 2006-03-11
Posts: 3

Re: i need help with this math problem

I got 6 martians and 8 earthlings.

Everyone had 2 eyes at least so that would be 14*2=28 take 28 from 34 and you know that you need 6 martains to equal 34 eyes!?down or up      dunno

Last edited by damathgirl (2006-03-12 05:50:41)

Offline

#8 2006-03-12 08:22:45

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,626

Re: i need help with this math problem

That works!


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

Offline

#9 2006-03-12 09:40:26

mikau
Member
Registered: 2005-08-22
Posts: 1,504

Re: i need help with this math problem

Problems that involve martians are always funner.


A logarithm is just a misspelled algorithm.

Offline

#10 2006-03-12 09:52:07

ashwil
Member
Registered: 2006-02-27
Posts: 121

Re: i need help with this math problem

I took the question literally:

14 people (humans) = 28 eyes
2 martians = 6 eyes

Offline

Board footer

Powered by FluxBB