The mean is found by adding the numbers and dividing the sum by the number of numbers in the list. So 4+11+15+7+11+11+3+7= 69/8=8.625 in the tenths place is 8.6. The median is the middle value in a list ordered from smallest to largest. So 3, 4, 7, 7, 11, 11, 11, 15, the meadian is 7 because it is the middle value.
Construct the line using the two points: slope: m = (-4 - 2) / (4 + 3) = -6/7; then, y = mx + b => 2 = (-6/7)(-3) + b => 14/7 - 18/7 = b => b = -4/7. And your y-intersect is -4/7.
