I used [‘Engine size’, ‘Cylinders’, ‘City’, ‘Highway’, ‘Combined’,
‘Combined (mpg)’, ‘CO2 emissions’]
The grader feedback unclear to me:
Failed test case: You have some extra features in your list of numeric_features.
Failed test case: correlation_matrix has an incorrect value. Please check your correlation matrix.
Hello, @Lam_Chou_Vun_Dennis,
Please check out the extra hint above the cell by clicking on it and it will expand.
While it has explained it, I want to add that we don’t just consider a feature populated with numbers as numeric feature, because ordinal feature and categorical feature may also be numbers. For categorical, it is super clear because its values don’t have to preserve any meaning of ordering. 
For ex 3, try again after passing ex 2 because the former depends on the latter.
Cheers,
Raymond
OK all done.
Hello Mr. Raymond,
Am too stuck in this exercise - # GRADED CELL: Exercise 2 (Analyzing car CO2)
Whatever knowledge I gathered, I made this following code. Please let me know, if I miss anything. I followed the hint als. Thanks in advance.
### START CODE HERE ###
# mentor edit: code removed
### END CODE HERE ###
plt.show()
Sorry to say, posting your code on the forum is not allowed by the Code of Conduct.
I have edited your message.
@bgopal What error do you get, could you please elaborate
my bad. Apologies. Cracked the code with the help of one forum members. Thanks TMosh.
Good morning, how are you?
I’m having trouble with the analyzing-car-co2 exercise. The error I’m getting is: The object required for grading cannot be found in your code.
I don’t want to violate the code of ethics, but the order of my columns is: Es, Cty, Hiy, Comb, Comb(), CO2
Hi Federico!
Issues with `object required for grading not found` are almost always fixed when you reset your notebook. You can follow the instructions here in order to do so. Good luck
rebooted and ex 2 was fixed, now I have 10/10 
The problem is the 3rd one below: Failed test case: correlation_matrix has an incorrect value. Please check your correlation matrix..
I am also having the same problem with excercise 2 and 3
Hello @iykm2025, could you post this on a new topic with relevant screenshot. And expand on the details on why it does not work at your end (with the grader output)
Remember, the hint and directions is provided within the assignments.
My advice is to look closely at how you select your columns in Ex02. You need to define the specific numerical features and make sure they are passed inside brackets when indexing the DataFrame. Once you have that set up, Ex03 is identical in terms of which columns you are selecting to build the correlation matrix. Good luck.
Thanks @AflahZ. Ihave posted it