Is this correct? be honest and correct me anything

Number 2 is wrong because it says NO more than so it would be the opposite of a more than sign. So it should be a less than or equal to sign.
The same goes for number 4. 
Number 5 is wrong as well because since it is the maximum then it cannot be higher than 8, so there so be a less than or equal to sign.

16pi

Step-by-step explanation:

have a good day:)