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I always start the semester with this article, Why American Consumers Can’t Add:

American Innumeracy


It was written in 2009 right after the financial collapse, but it is still very relevant with nice statistics that set the stage for developing the fundamental skill set for quantitative literacy.  The reasons for the subprime housing bubble quickly take us to the National Assessment of Adult Literacy (NAAL) and the fact that Americans are much worse at math than most of us would think.  The NAAL is where I get the statistic that 87% of adults are quantitatively illiterate in this country, with only 20% being able to reliably calculate mortgage interest and 20% being unable to calculate weekly pay from an hourly rate.  Over half the adults in the U.S. cannot

  • compute the total order from a sales catalog
  • determine if they have enough gas to reach the nearest gas station
  • calculate the cost of a child as a % of their budget

NAAL results

The author of the article, Bob Sullivan, closes with a stark admonition about the “hidden epidemic of innumeracy” that will doom us to repeat our fiscal mistakes.  The good news is that our QR courses are taking up the challenge and addressing this quantitative illiteracy head on!

On the take home quiz I ask the following questions:

  1. a)   You and a friend go down to The Gelato Fiasco and order two items: one costs $4.50 and the other $3.75.  What would be a 15% tip for the combined total?
    b)   20% tip is how much more than a 15% tip? Hint: This one is tricky (which isn’t much of a hint but you get the idea).

    1. 5% more
    2. 10% more
    3. 25% more
    4. 33% more
  1. If a person borrows $450 at the beginning of the month and promises to pay back $543.75 on payday at the end of the month, what is their monthly interest rate? What is the associated APR of this payday loan?
  1. Compute the amount of money US adults spend each year on getting tax preparation help for the 1040 EZ form (the information you need is in the article!).
  1. Joel Best’s nomination for the “worst statistic ever” is a mutation of the original “The number of American children killed each year by guns has doubled since 1950.” Reword this sentence so that it means if the number killed in 1950 was 1 then in 1951 the number killed would be 2 then the next year 4 then 8 etc.
  1. Does the doubling of childhood gunshot deaths from 1950 to 1994 mean our society has become more violent? Explain!




2 thoughts on “Innumeracy

  1. 1B has to be 5% correct? it says it’s tricky so I assume it is not but no matter what I do I still come up with 5%


    Posted by Ashley | September 29, 2015, 8:33 pm
    • It is the same thing as the percent difference between $20 and $15. $20 is $5 more than $15 (total difference) but is $20 only 5% more than $15? Of course, we need a good understanding of what it means to say something is “5% more than”. As a hint: $22 is 10% more than $20.


      Posted by egaze | September 29, 2015, 8:56 pm

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