Thank you for the opportunity to help you with your question!
Significant figures have certain rules to them. When trying to understand how many numbers should go after the decimal, you look at the existing numbers. So for your problem we see
25.36 (two numbers after decimal)
4.15 ( two numbers after decimal)
2.316 (three numbers after decimal.
By the rules of significant figures, you pick the number with the greatest number of significant figures after the decimal place (when looking for after the decimal place). In this case, it is three.
Therefore, you do not have enough significant figures when it is 9.15. That is why it had you round to 9.154.
I have done such research for your question, and I must have remembered it wrong. Your teacher is correct, you are supposed to round to the least number of significant figs.
25.36 (4 significant figures)
4.15 (3 significant figures)
2.316 ( 4 signficant figures)
Therefore it should be 9.15.
I am truly sorry for my mistake.
None the less, it should not be 9.154 as stated. It is most likely a mistake, and you found it!
Here is the website I was looking at, if you were curious as to what research I did. It might be helpful.
Content will be erased after question is completed.