Mixture - Amount Used

[Guest]

A grocer wants to mix 30 lbs. of candy at $6 per lb. with candy at $3 per lb. to obtain a mixture at $5 per lb. Determine amount of $3 candy used.

Let x = amount of $3 candy.

I am confused on how to solve.

[Guest]

its back to the same old problem.....setup an equation describing the facts you know.

You are trying to find the amount of $3 candy so let it equal X as you have done

The amount of the individual candies before = the total amount used in the mix
and the cost of the items before = the cost of the mixed items

30 of candy1 + X of candy2 = (30 + X) of candymix

30 x 6 + X x 3 = 5(30 + X)

180 + 3X = 150 + 5X

30 = 2X

X = 15 lbs

So 15 lbs of $3 candy used with the 30 lbs of $6 candy......

So you will have 45 lbs of $5 mix

[Guest]

Thanks. I understand now.

[Guest]

One more for a spreadsheet:

180 + 3X = 150 + 5X

180 + 3(A2) = 150 + 5(A2) ??

I am not sure about adding these type formulas. The only info I could locate in the "Help" or "?" file is for basic formulas, unless I am looking in the wrong area.

[Guest]

These are equations and not really formulas as such that you enter in a cell......

180 + 3X = 150 + 5X

180 + 3(A2) = 150 + 5(A2) ??

Are you wanting to put this all in a single cell and get an answer.??? [180 + 3X = 150 + 5X] ....that will not work.

Also...[180 + 3(A2) = 150 + 5(A2)] in a single cell will not work either.

If you put [=(180 + 3*A2)] in a cell say B5 and [=(150 + 5*A2)] in another cell say D5. You can play a guessing game by entering numbers into cell A2 and see what number in A2 makes both cells B5 and D5 equal. At that point you have solved the equation. the [] brackets are not needed only here to group.

OR

Re-arrange the original equation as.............

5X - 3X = 180 - 150

X(5 - 3) = 180 - 150

X = (180 - 150) / (5 - 3)

Now if you work this out on a calculator you will get the answer 15 for X ....so X = 15 and solves the equation.

You can instead put the RHS...... [=(180 - 150) / (5 - 3)] in a cell and excel will work it out like a calculator. The cell will show 15.
The [] square brackets are not needed only here to show what is in cell.

OR

You can put all the individual numbers in separate cells and put the formula in another cell

In B5 put 180
In B6 put 150
In B7 put 5
In B8 put 3

in B10 put =(B5-B6)/(B7-B8) ......the refs will refer to the numbers in B5 to B8 and work out calc. as before. Cell should show 15.

If you change any of the numbers in cells B5 to B8 you will see the answer change. So you can solve for X for any equation of the same form as your original but with different numbers.

[Guest]

Thanks.

[leesajohnson]

30 of candy1 + X of candy2 = (30 + X) of candymix

30 x 6 + X x 3 = 5(30 + X)

180 + 3X = 150 + 5X

30 = 2X

X = 15 lbs

So 15 lbs of $3 candy used with the 30 lbs of $6 candy

45 lbs of $5 mix

[Guest]

a very good copy of an earlier post.......well done......