That value may look close, but it’s actually incorrect. It most likely means that you took the sample code they gave you as the complete solution, but it’s not. They actually said that in the instructions, but apparently they were a little too subtle about it. 
Compare that code to the mathematical formula for the cost shown just above and ask yourself two questions:
- What happened to the factor of \frac {1}{m}?
- Why is there only one term? What happened to the Y = 0 term?