Question

Distribution with a mean of 100 and standard deviation of 15...

Answer 1

Use the z-score:
                                      112 - 100
For 112, the z-score is --------------- = 12/15, or 0.8.  
                                             15

Next, find the AREA under the standard normal curve TO THE LEFT OF 0.8.

Use either a z-score table or a calculator for this purpose.

Using my calculator, I found that this area is 0.532.  That places 112 in the 53rd percentile.

82 would be in a lower percentile:  the 12th percentile.

Let me know if you have questions about how to use a calculator to do these calculations.