Jeff Rossen Gets An "F" In Math

Can someone please buy Jeff Rossen a calculator? On Saturday's Nightly News, Rossen told us that the year-to-date murder rate in Chicago had risen from 81 last year to 97 this year, a 16.5% increase. Wrong. That actually represents a 19.75% increase. Here's a tutorial for Rossen and his producers: Let's say the murder rate in Metropolis increased from 100 in year 1 to 150 in year 2. Common sense and logic tell us that that represents an increase of 50%. The way we get that mathematically is to take the difference in murders from year 1 to year 2 (50) and divide that by the number of murders in year 1 (100). 50 divided by 100 is .5, so that means the murder rate increased by 50%. Now let's apply that formula to Rossen's Chicago figures. The difference in murders from year 1 to year 2 is 16. We divide that by the number of murders in year 1 (81). 16 divided by 81 is .1975, so the murder rate went up by 19.75%, not 16.5%. This isn't rocket science. It's junior high school algebra. If Rossen and his producers can't calculate a simple increase in a murder rate, how can we trust them with the really difficult stuff?