For ICSE 10th Mathematics the most important portion in Statistics (topic of Mathematics) is the drawing of Histogram and Ogive. So if you learn this topics then you will get atleast one broad question from this topic. Apart from this Mean, Median and Mode is also scoring. So I would say, don't leave any topic of Statistics as it's very easy and with a little bit of practice you can master it.

The probability portions consist of some of the topics such as Random experiments, Sample space, Events, Definition of probability, Simple problems on single events. Just go through easy problems in this topics and learn the definition well.

Overall in ICSE Mathematics, I would say statistics is the most scoring part.

To know more about ICSE 10th, visit the link below:

https://school.careers360.com/boards/cisce/icse-10th-syllabus

I hope this answer helps. All the very best for your future endeavors!