Hello.

Usually to get a good percentile in CAT exam you will have to solve around 50 questions with an accuracy of 90%.

If you cover these topics then you can easily solve 18-20 questions:

1.  Number system which covers the highest weightage is in the quant section that is around 7 - 9 questions.

2. Arithmetic

3. Logarithmic covers usually two to  three questions which are doable.

4. Commercial mathematics and mensuration.

You can have a look over this website as it will help you analyse the CAT 2020:

https://bschool.careers360.com/exams/cat