to find mean, add all the numbers, then divide that by how many numbers there are. so: (10+31+36+36+38+42+47+48+49+52)/10 = 389/10 = 38.9
to find the median, you arrange the numbers from smallest to largest, and the one in the middle is the median. in this case, there are 2: 38 and 42. so now we need to add these then divide by 2: 80/2 = 40