Help with calculating percentages and distribution

Hello!

I am new to the forum and in need of your help (no surprise there).

So, I am studying Veterinary Medicine (I am in the first semester) and I have an assignment on Excel that our professor just gave us without any instructions since as he says...Google has everything.

I did most of it but I am stuck in a couple of things and I thought maybe you could point me in the right direction.

Firstly, I calculated the age of about 650 cows in years based on the data that our professor provided us with. However, I also need to calculate the % of these cows that are under the age of 3. Now, the ages are all in a column, that is K2-K650 but I don't know what formula to use. I think one way to do it is with the IF formula but I haven't fully understood how to do that...

Lastly, I have to find the age distribution of these cows but again I can't get it right.

I would really appreciate any advice you might have on these two problems!
Thanks in advance

Thank you very much!
It worked :D