The mean is the average (add up all he numbers then divide by how many numbers there are). So in this case we would do 153 + 176 + 249 + 150 + 620 + 242 which is 1,590. Then we divide that answer by 6 because there are 6 numbers. 1,590 ÷ 6 is 265, which is the mean. I hope this helps!!