Question

Why isn't this equal to 10? (approximate areas)

Answer 1

You have not provided much information, but I'm going to guess that you have assumed an OVER estimate is a RIGHT estimate.

If you want an OVER estimate from your four intervals, you must pick the Right Coordinate where the function is increasing and the Left coordinate where function is decreasing. In your case, the first two are righties and the last two are lefties.

Answer 2

your n = 4
set up your summation