Tuesday, September 2, 2014

238: Skew

Given the same numbers as yesterday:

12783, 12784, 12785, 12790, 12792, 12795, 12799, 12811 

What characteristics can we look at to tell whether this data is skewed?

Monday, September 1, 2014

237: Average

Given the numbers:

12783, 12784, 12785, 12795, 12792, 12790, 12799, 12801 

There are a lot of tricks and shortcuts, and of course, the pencil and paper add-em-up method of finding the average of a set of numbers.
What's your best way to get the average of those eight numbers?

Sunday, August 31, 2014

236: Make the area Unique


Can we solve for area? If not, what different additional information could be added?

235: Counterfeit Bill

The Counterfeit Bill problem (Sobel and Maletsky 1999).

A customer enters a store and purchases a pair of slippers for $5, paying for the purchase with a $20 bill. The merchant, unable to make change, asks the grocer next door to change the bill. The merchant then gives the customer the slippers and $15 change. 

After the customer leaves, the grocer discovers that the $20 bill is counterfeit and demands that the shoe-store owner make good for it. The shoe-store owner does so, and by law is obligated to turn the counterfeit bill over to the FBI. 

How much does the shoe-store owner lose in this transaction?

Saturday, August 30, 2014

234: Fraction Manipulation

I know how I would solve this problem, but not everyone is comfortable with algebra. Which ways can you come up with? Which seems the best to you?

There is a number such that, when it is subtracted from the numerator of the fraction $\dfrac{5323}{7577}$ and added to the denominator, the fraction reduces to $\dfrac{17}{83}$. Determine the number.

Friday, August 29, 2014

233: Vegetable Zen


100 students were surveyed about their preferences for bell peppers (capsicum), carrots and spinach, with the following results:

①  72 students said they like bell peppers, and 36 students said they like only bell peppers.
②  41 students said they like carrots, and 9 students said they like only carrots.
③  31 students said they like spinach, and 3 students said they like only spinach.
④  9 students said they like neither bell peppers, nor carrots, nor spinach.

What is the best way to model/analyze this survey data?

Graphically (and what type of graph)?
Tables? How?
Algebra?


source.

Thursday, August 28, 2014

232: Area

What are some ways to find this area?
Which way gives you the most satisfaction?

source.