Minus' Solution to

Cash for Cats
Posted Weeks of April 20 - May 3, 1998

You could solve this using an algebraic formula, or by trial and error. Let's try the trial and error method.

If they each sell 400, Samantha makes 0.1(400)(100) = $4000
Tabitha makes $10 for the first ten, $20 for the second ten, $30 for the third ten. So, by the 39th ten Tabitha is making $390 (for that ten). Which means by 400 sales, Tabitha is making 39%, or: 10 + 20 + 30 + ... + 390 = 10(1 + 2 + ... + 39) = 10[39(40)/2] =  $7800

This means they sold fewer than 400 bionic kittens.

............................................

Let's try 200. Which means Samantha makes $2000 and Tabitha makes:
10[20(21)/2] = $2100.

They sold a little less than 200 bionic kittens.

............................................

Let's try 180. Which means Samantha makes $1800 and Tabitha makes:
10[18(19)/2] = $1710.

............................................

Let's try 190. Which means Samantha makes $1900 and Tabitha makes:
10[19(20)/2] = $1900.

If Samantha and Tabitha each sell 190 bionic kittens, they will make the same amount.


Your Solutions

Dane Coalson and Caroline Warburton, from Pulaski Middle School, plotted out their solution like so. A nicely organized dish like this deserves recognition!

Cats Sold      Samantha's Profit          Tabitha's Profit
    10                  100                     10
    10                  100                     20
    10                  100                     30
    10                  100                     40
    10                  100                     50
    10                  100                     60
    10                  100                     70
    10                  100                     80
    10                  100                     90
    10                  100                    100
    10                  100                    110
    10                  100                    120
    10                  100                    130
    10                  100                    140
    10                  100                    150
    10                  100                    160
    10                  100                    170
    10                  100                    180
    10                  100                    190
Totals:  190          $1900                   $1900

Ben Gill, of Kent Street Senior High School in Western Australia, also choose to plot the solution out. He based his table on Tabitha's commission. Delightful!
Samantha and Tabitha each sell 190 toys and earn a commission of $1,900.
              % of commission 
  # sold        (for Tabitha)      commission paid   total earnings 

    10              1%                   $10             $10
    20              2%                   $20             $30
    30              3%                   $30             $60
    40              4%                   $40            $100
    50              5%                   $50            $150
     ~               ~                     ~               ~
   100             10%                  $100            $550
   110             11%                  $110            $660
   120             12%                  $120            $780
   130             13%                  $130            $910
   140             14%                  $140            $1050
   150             15%                  $150            $1200
   160             16%                  $160            $1360
   170             17%                  $170            $1530
   180             18%                  $180            $1710
   190             19%                  $190            $1900

If Samantha sells 190 toys at 10% commission she makes 10% of $19,000
which is also = $1,900. Therefore, they sell 190 toys each.

The following chefs also provided Minus with solutions. Most of which were tables, and a few were just plain answers. No one provided us with the correct algebraic formula. Aww...that's okay. Minus only likes the fresh stuff anyways... Yuk! Yuk!
Verni Sundararajan [verni@hotmail.com]

Eloise Fardon of St. Hilda's in Western Australia

Dave A.K.A: I-Wanna-Harder-Challenge Man [mckechnied@cses.scbe.on.ca]

Kamala Gracie of St Hilda's in Western Australia



Being a Seinfeld fan,
Minus offers you all a fond

"Yada, yada, yada..."