Monday, August 8, 2011

Years of CNBC Math Mistakes

Below is the letter that I wrote to CNBC World:

For years I have noticed that your reporters (both CNBC and CNBC World) have problems with their math. Today at around 3:15am, I heard Claudia from Milan reporting on your network that a certain stock was "up by six percentage points". Since stocks are measured in points, it is mathematically incorrect to say that a stock is up by a certain number of "percentage points". Stocks aren't measured in percentage points. A stock increases by a unitless percent. It makes no more sense to say that a stock is "up by six percentage points" than it does to say that a stock is "up by six oranges". The only things that increase by percentage points are those that are actually measured in percentage points. If Bernanke were to raise the Fed Funds rate from 0.25% to 0.50% that would be an increase of 0.25 percentage points but since the rate doubled, it actually increased by 100%. Clearly percentage points and percents are two completely different things. So this is why is hurts my ears to hear your reporters use "percentage point" when they should be saying "percent", perhaps in an unconscious effort to sound more official. But what they are saying is mathematically nonsensical. I expect better from a financial network.




Best regards,


Mark Kronenberg
Founder, Math 1-2-3®, Inc.
Specialists in Math Tutoring & Test Prep
888-math123
www.math123.com

Sunday, February 20, 2011

Never Take Numbers At Face Value. The Wall Street Journal Could Use An SAT Math Tutor in NYC

I'm always on the lookout for math mistakes on TV and the radio. I hear them frequently on CNBC, Fox Business News, Bloomberg, etc. But now even the Wall Street Journal has let me down.  Is nothing sacred?! A friend just brought this to my attention re: the cost of a Maybach.

The article states that the car sells for $459,000 in the U.S. but sells for $1,000,000 in Hong Kong because "the biggest reason for its high price is the Hong Kong luxury tax, about 50%". But if a $459,000 price is jacked up to $1,000,000, the tax alone is $541,000, over 100% of the original price.

Amy Ma, the author of the article fell into one of the classic traps that an SAT Math Tutor in NYC would avoid: thinking that percents operate the same way in both directions. In round numbers, the price of the Maybach is $500,000 in the U.S. and $1,000,000 in Hong Kong. Yes, 50% of the after tax price is tax, but the SAT trap is to say the tax is $500,000 out of $1,000,000 = 50%. When calculating percents, always bear in mind the starting point of the calculation. A 50% tax implies a 50% tax on the starting (i.e., pre-tax) price. A 50% tax on a $500,000 car is $250,000, yielding an after tax price of $750,000.

According to Hong Kong Regulations, a $459,000 car should actually be $744,150 in Hong Kong after a tax of about 62%. Since the 62% "registration tax" is much greater than the 50% luxury tax mentioned in the article, the 50% tax can't be the biggest reason (as the author claims) for the big price tag.

At best, the author hasn't clearly explained how the price continues to rise from about $750,000 to about $1,000,000. But if the car actually does cost $1,000,000 in Hong Kong, the good news for Hong Kong residents is that moving to the U.S. gives them a 50% discount on the car.

Click here for top NYC math specialists who don't fall into SAT traps.

Saturday, February 19, 2011

Math 1-2-3® Pays Its Tutors 10 Times What The Competition Pays

I'm Mark Kronenberg, founder and CEO of Math 1-2-3, Inc. We regularly research our competition. Today I found a Help Wanted ad on Craigslist. The ad was from a learning center that has 3 students for 1 tutor. The total amount they bill the 3 students is about $165/hr. ($55/hr./student). The "tutor" (actually a teacher because not a private instructor) is paid $12-$16/hr. which is less than 10% of what the teacher is billed out for. Not only is this an insult to the tutor, the quality of the instructor is statistically likely to be poor because the wage is too close to the neighborhood of McDonald's wages. Math 1-2-3® pays its tutors the lion's share of the billable amount. We seek to attract and retain top talent so we pay an amount that is as much as (or sometimes more than) what they could net on their own after marketing expenses. Our tutors are the highest paid in the industry.

We invest in our tutors because they are our top resource. We charge accordingly.  For our clientele, price is not part of the equation. They shop solely on quality and demand the best. For the last 16 years, we have fulfilled this mission with our top 1% talent math specialists.