A) According to U.S. Department of Health and Human Services (https://medlineplus.gov/ency/article/003399.htm) the normal heart rate (pulse rate) for children 10 years and older is 60 to100 beats per minute.
C) However as some research shows (see, for example, https://www.ncbi.nlm.nih.gov/pubmed/25439450), that it is decrease after 50 years to 54 beats per second.
B) A normal recovery (target) heart rate for 15-17 ears is 100-170 bpm (see https://sites.google.com/site/drnormanherr/CSCS-Activities/cscs-investigations---biology/recovery-heart-rate). It is also decreased with age,
D) Determining a normal or average pulse rate for the class might be bad idea. Consider the situation when two persons have lower and higher heart rate than normal. For example, one has 40 bpm and another has 120. Average of this two values is 80 bpm which is absolutly normal, but neither first nor second is in normal state. Also, the heart rate seems to be rather individual and normal value for one person will not be shuch for another.