I can answer questions 34 out of 40 correctly…

[Silverobama]

I’ve been preparing for my IELTS and I’ve finished answering many questions in the reading sections. On average, my correct answers are around 34 out of 40.

I wrote a sentence to express the meaning:

I can answer questions 34 out of 40 correctly on average in reading part.

Is my italic sentence natural?

 

[5jj]

I can answer 34 out of 40 questions correctly on average in the reading part.

 

[emsr2d2]

The tone of your sentence is quite formal. I don't know who you plan to say this to but, for info, here's what I would say if I were talking to another native English speaker:

I usually get about 34 out of 40 on the practice reading tests.

Using the structure "XX out of YY", in BrE at least, is automatically taken to mean that you got XX (number) of answers correct out of a possible YY (number). The associated verb for most of us is "get".
I can count on the fingers of one hand the number of times I've used "correct/correctly/incorrect/incorrectly" in real-life conversations with other native English speakers. I use "right/wrong".

How many did you get right?
I'll probably get them all wrong.
I got 13 wrong.
At least I got some right!

 

[Tarheel]

This is just one American speaking, of course, but I'd say American English is no different.

 

[Silverobama]

One of my friends got [delete 'a' or write 'an'] 8.5 for his speaking part.

I'll write down all these sentences down in my notebook too.