Minus' Solution to

Many Mobiles for Minnie
Posted Weeks of June 15 - 28, 1998

Minus apologizes for blundering this question. A small typo in the original question led to cars in fractions for the solution. Cars, of course, don't come in 1/3 and 2/3--unless you're shopping for an auto in a scrap heap. Forgive our math mascot. He's just getting old like the rest of us.

500 Mathmobiles and 300 GeoMobiles

25% of each type were white, so 125 white MM and 75 GM
15% of each type were blue, so 75 MM and 45 GM
10% of each type were black, so 50 MM and 30 GM
8% of each type were red, so 40 MM and 24 GM

290 MM and 174 GM accounted for
210 MM and 126 GM remaining

16 MM were purple, which makes 194 MM remaining. Twice as many Mathmobiles were painted in a psychedelic design as were painted yellow. And twice as many Geomobiles were painted yellow as were painted psychedelic. 129 1/3 MM were psychedelic. 64 2/3 MM were yellow.   42 GM were psychedelic and 84 GM were yellow.

Your Solutions

This treat comes from Sek and Saba, of Christ Church Grammar School and Methodist Ladies' College in Western Australia. It's a real taste-bud ripper!

There were 500 mathmobiles and 300 geomobiles.

Of these 58% altogether are white, black, blue and red. Thus, this is 484 which are either of these colours. Thus, 800 - 484 = 336 are neither white, blue, black and red.

Of these 336 cars, 210 were mathmobiles and 126 were geomobiles.

16 of the mathmobiles are purple.  There thus are 194 yellow or psychedelic cars left. If there are x yellow mathmobiles, then there must be 2x psychedelic mathmobiles. Therefore, there are 64 and 2 thirds yellow mathmobiles and 129 and a third psychedelic mathmobiles. Round to the nearest whole number and we obtain 64 yellow mathmobiles and 129 psychedelic mathmobiles.

Of the 126 geomobiles left, 2 thirds of them are yellow, and 1 third of them are psychedelic. Thus, 84 geomobiles are yellow and 42 are psychedelic.

Thus, Minnie can choose from 64 yellow mathmobiles and 84 yellow geomobiles.

The Great Western Australia cook-off produced another fantabulous dish. This one comes courtesy of Chris and Jeanette.
My answer is: There are 64.66666 recurring yellow Mathmobiles and 84 yellow Geomobiles.

We figured that 42% of all cars would be purple, yellow and psychedelic cars.   42% of 500 Mathmobiles is 210 and then we subtract the 16 purple cars and were left with 194 mathmobiles.  There were twice as many psychedelic cars as there were yellow so we divided 194 by 3 to get the amount of yellow cars. We found out that there were 64.6 recurring yellow cars.

We then figured out 42% of 300 Geomobiles to get the number of yellow and psychedelic cars seeing that there were no purple Geomobiles. 42% of 300 Geomobiles was 126. there were twice as many yellow cxars as there were psychedelic cars, so we divided 126 by three to get a third of the geomobiles which was the number of psychedelic Geomobiles. We then multiplied the number of pyschedelic cars which was 42, by two to get the number of yellow cars. We then came to the conclusion that there were 84 yellow Geomobiles.

Team Three, consisting of Emily and Jeremy, also came through with an intriguing solution. This duo didn't add any frills or chills. They just let the ingredients do the talking.
20 + 15 + 10 + 8 = 58%. Therefore 42% are purple/psychedelic/yellow.

500 * 0.42 = 210

210 - 16 = 194

194/3 = 64.6 recurring. Therefore there are approximately 65 yellow mathomobiles.

300 * 0.42 = 126

126/3 = 42

42 * 2 = 84. Therefore there are approximately 84 yellow geomobiles.

Vivian wasn't going to let Minus get away with a silly question. She let our mascot know with a not-so-subtle punch in the shark gut. Ouch!
Dear Mr Minus, this was a pretty silly question, my answers were there are 84 yellow geomobiles and 64 2/3 yellow math mobiles, and i don't know y u would sell 2/3 of a car!

Since there were 500 mathmobiles (mm) and 300 geomobiles(gm) and 58% of them were not yellow, we end up with 210mm and 126gm. Since 16mm were purple, we have 194mm and 125gm. Of these, twice as many Mathmobiles were painted in a psychedelic design as were painted yellow, so 1/3 mm were yellow - 64 2/3. Of the gms, twice as many Geomobiles were painted yellow as were painted psychedelic, so 2/3's of the gms  were yellow - 84.

A slightly embarassed Minus has slipped out the back door. Nevertheless, he wants to give all his feeders a big warm thanks for being so forgiving.
David and Teresa of CCGS and MLC in Western Australia

Yung and Tracy of MLC in Western Australia

Jim and Caitlin of CCGS and MLC, Year 9, Maths Web Weekend

Nick and Kathryn

Caroline and George

R. Donraadt of CCGS in Western Australia

David Cruise, Hugh McCann & Kameron Stein of CCGS in Western Australia

Pallas Stewart of St. Hilda's A.S.G.

Math mascot with good appetite for
questions and excellent typing skills.
Please inquire within.
(We're just kidding, Minus!)