Buzz: Product Feedback

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!