P-R intervals measures time during what

Explanation:

The first measurement is known as the "P-R interval" and is measured from the beginning of the upslope of the P wave to the beginning of the QRS wave. This measurement should be 0.12-0.20 seconds, or 3-5 small squares in duration.

boys: median=50, mean=46

Girls: median= 33, mean=34

Step-by-step explanation:

Mean is the average. Median is the middle number. Both groups had 10 scores. Boys ranged from 15-81. Girls from 0-75; their mean & median would be less because their scores are less.