11.5 on the 100 meter dash, is it good for a 9th grader guy?

Yes, this is MORE than good.

There is a precise way to answer your question though, using the statistical analysis done by the WMA (see link). However, the precision of the analysis depends on two assumptions not confirmed in your question:

1) 11.50 is a fully automatic time (FAT). If not, add 0.24 seconds to this time.

2) Your age is exactly 15.0. If not, enter your precise age in decimals in the age input box. eg 15 and 6 mos = 15.5

The result:

For a 15.0 yr old male, 100m of 11.5 secs = 90.6% of the world standard for this age and gender. 90% and above is considered competitive at the world-class level. The "world standard" referenced here is 10.42 seconds and is the statistically-extrapolated world record for this age and gender.