0
$\begingroup$

Ok so I already know how to throw a word problem into a mixture solution table. In this situation I am going to go ahead and throw the equation at you guys and see if you can help me figure out this equation.

$$.1x + .4(100 - x) = 31$$

So this is what I would do:

$$(.1x / 100 ) + (.4 / 100)(100 - x) = 31$$

which turns into:

$$(100)(.1x / 100 ) + (.4 / 100)(100 - x) = 31(100)$$

which turns into:

$$1 + 4(100 - x) = 3100$$

and so on...

I recently found out I was not supposed to divide the $.1x$ and $.4$ by $100$, but divide by $10$ instead of $100$.

This baffles me, why would I divide the decimals by $10$ instead of $100$?

$\endgroup$
  • $\begingroup$ Your last equation is missing something: the $ \ x \ $ that was present in the first term all along the way has suddenly disappeared. You should have $ \ x \ + \ 4 \ (100 - x ) \ = \ 310 \ , $ as otherwise corrected by nagniemerg. $\endgroup$ – colormegone Jan 22 '14 at 5:24
1
$\begingroup$

When you multiply .1 by 100, you do not get 1. That is .1 = 1/10 and not 1/100.

So then your equation becomes

10 + 40(100-x) = 3100.

You could have just multiplied by 10 instead and gotten

1 + 4(100-x) = 310.

Solve for x.

$\endgroup$
  • 1
    $\begingroup$ And now my mind has been blown. Thank you so much, I feel so dumb now haha. It is just simple math, here I am just trying to follow step 1, 2, and 3 instead of actually trying out to see what happens when you multiply 100 by .1. blah $\endgroup$ – User 101 Jan 22 '14 at 4:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.