# Buzz: Product Feedback

## Flexibility wanted with variables

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Feature idea (LEVEL 2)

It would be great if variables could refer to other variables.

For example, Kevin McBride contacted me with this particular problem.

He wanted to set up a problem where students were given a number and told that it was a certain fraction of a whole.  They were then to calculate the whole.

In other words:

If x is y/z of the whole, then what is the whole?

Answer=x/y*z.

If 15 is 3/4, what is the whole?

Answer= 20

Here's the catch, he wants the x variable to be a multiple of the y variable.  He would also like the z variable to always be greater than the y variable but less than 14.

His solution so far has been to create a separate problem for each y.  Here's a few examples:

Type: F
Options: Number
Score: 2, Partial, Round
Groups: WhatIsWhole
Var: x = 3,6,9,12,15,18,21,24,27,30,33,36
Var: y = 3
Var: z = 4..13
7) If $x$ is $\small \frac{$y$}{$z$}$ of the whole, what is the whole?
_____
@ The correct answer is $eval($x$/$y$*$z$,#) a.$x$/$y$*$z$//What is whole? Numerator is 3 Type: F Options: Number Score: 2, Partial, Round Groups: WhatIsWhole Var: x = 4,8,12,16,20,24,28,32,36,40,44,48 Var: y = 4 Var: z = 5..13 8) If$x$is $ \small \frac{$y$}{$z$} $ of the whole , what is the whole? _____ @ The correct answer is$eval($x$/$y$*$z$,#)
a. $x$/$y$*$z$
//What is whole? Numerator is 4

So, what we would really like to see is something like this:

Type: F
Options: Number
Score: 2, Partial, Round
Groups: WhatIsWhole

Var: w = 1..12

Var: y = 3..12

Var: x = $y$*$w$

Var: z = ($y$+1)..13

8) If $x$ is $\small \frac{$y$}{$z$}$ of the whole , what is the whole?
_____
@ The correct answer is $eval($x$/$y$*$z$,#) a.$x$/$y$*$z\$
//What is whole? Given is multiple of numerator up to 12; numerator bounded by 3 and 12; denominator larger than numerator, bounded by 13

Does that make sense?

Please let me know what questions you have.

Thanks!

### Comments (1)

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This is one of my top three requests for variables!

1. Allow the ability to define a variable from another variable.
2. Allow the ability to define student input as a variable.
3. Have a global variable for an assignment (Currently variables are either course or question, nothing in between.)
2
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