I know you all have your conspiracy theories that a miner must steal your hashrate, but i will have to dissapoint you.
Your math is bad, to get average of something you divide total with something, in this case :
Total time in seconds since connected to pool / total number of sent shares (good & bad)
And end of story. This is how you get average time needed to find a share.
Sorry im not stealing 9% of your hashrate.
Your case:
Mining time 15 hours, 3 minutes 10 seconds = 54190 sec (in this case this can be taken because you did not have pool disconnects)
Total shares : 1213
Average : 54190 / 1213 = 44.6 sec
Now check your screenshot.
Thanks for the reply, dear! There were no thoughts about theft of hash. Based on your mathematics, you can calculate the real hash of the miner 1213 * 240000 = 291120000 total hash. 291120000 h / 54190 sec =
5372 h/s. Why then this figure is obtained, not
5800? What am I doing wrong?
too much theory guys. Better take a 24,48h average from the pool, at the end that's what really matters.
If you get numbers you don't like, switch mining software

Don't get mad, but i really don't have time and nerves for these kind of things.
I mean if your point isn't that the miner/me is stealing from you, then what is it? What are you trying to say ?
I'm mining Monero, SRB reports 2580 H/s, Nanopool 2 hour SMA flutuates slightly from 2520 to 2677 H/s.
Seems more than fine to me.