Question on microeconomics

[FishNDip]

Hello, So I'm not sure if this is the right place to ask this, but I'm doing Microeconomics and I'm trying to find Marginal Cost. The formula Modern States gives me is  MC=(TC2-TC1)/(Q2-Q1) They tell me to fill out MC and I do it, but I'm getting 0.25 for the first answer instead of 1.25 and 0.5 for the second answer instead of 2.5. (Please view attachment for more info.)



Confused, I go looked up a khan Academy Video,
https://www.khanacademy.org/economics-fi...total-cost

I use the Formula Modern States gives me, and bingo! It works there, however I keep getting the wrong answers on Modern States.
Is Modern States wrong? Am I doing something wrong? Thanks for the help!

It looks like Modern States is wrong.

The AVC, ATC and MC for outputs 200 and 250 are incorrect as well.

Thank you! Needed a second opinion.