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mathfantasia
Jun 16, 2012, 09:15 AM
SO . . . wondering why the distributive property works? Want to average: 62, 63, 65, 67, 64, 68, 61, 64, 65, 65 in your head? Or maybe you're trying to quickly convert 1011001110 base 2 into octal.

Cool Math has these topics and more.

Here's a Freebie: Weighted Averages in Your Head. In a college class of 10 men and 15 women, the men scored an average of 87 and the women an average of 83. What is the average of the class?

The "classical" way: (10*87+15*83)/(10 + 15) = 84.6

The "cool" way: Subtract the lower test score from both test scores and take the weighted average. Then add back the lower test score to get the weighted average for the original problem.

In this problem: Subtract 83 from both averages. Men score 4 and women score 0. (4(10) + 0*15)/(10 + 15) = 40/25 which is 8/5 or 16/10 or 1.6. Add back the 83 and get 84.6

99 Cents at the moment.

http://itunes.apple.com/us/app/bsc-cool-math/id528528290?mt=8

Thanks for your support!



fossoway
Jun 19, 2012, 04:18 PM
I would recommend making the app free for the first few weeks to garner reviews. Maybe if you don't want to make it free, give some promo codes out to students or here on this forum. The screen shots of this app are sort of drab, and I fail to see why I would consider downloading something like this, and not one of the many other math review apps out there. Try writing a more detailed description, and work on spicing up the formatting.

mathfantasia
Jun 19, 2012, 06:35 PM
I would recommend making the app free for the first few weeks to garner reviews.

2 Apps that have already been submitted are this one in the forum (for free with advertisements), and the same program (with fonts adjusted) with ads for the iPhone/iTouch (submitted in the last week).

I fail to see why I would consider downloading something like this, and not one of the many other math review apps out there. Try writing a more detailed description, and work on spicing up the formatting.

A list of all available chapters and a summary of their contents are included in the App Description in the iTunes Store. Also, there are many tricks used here which are not taught in class.

I'll give a "check your polynomial" test freebie. How do you check if you have correctly multiplied (3x^2 + 2x + 4)(5x^3 + 6x + 1)? [NOTE: This trick has not been added to the app yet]

Is 15x^4 + 28x^3 + 30x^2 + 26x + 4 the right answer?
Is 15x^4 + 24x^3 + 35x^2 + 26x + 4 the right answer?
Is 15x^4 + 28x^3 + 35x^2 + 26x + 4 the right answer?
Is 15x^4 + 24x^3 + 30x^2 + 26x + 4 the right answer?

Substitution Test: If two polynomial expressions are the same, you can choose any value for the variable(s) and evaluate each expression. The two evaluations should be equal.

Basically you put in x = 1 and evaluate (although putting ANY number for x will work . . . usually you want to put in x = 1 and -1 and if they all check out you have a high chance of getting the correct answer). The expression in the problem is (3 + 2 + 5)(5 + 6 + 1) = 9 X 12 = 108. The correct expression in the answer list is: 15 + 28 + 35 + 26 + 4 = 50 + 30 + 28 = 108.