The following data have to do with the relationship between maternal smoking (# of cigarettes smoked per day,

which is variable X) and infant birth weight (which is variable Y). (X, X², Y, Y²,and XY have already been

calculated for you and are shown below in red font.)

Cigarettes Per Day (X) X² Infant Birth Weight (Y) Y² XY

24 7.5 56.2515.0

6367.2 51.84 43.2

10 100 6.9 47.6169.0

12 144 6.2 38.4474.4

14 196 5.8 33.64 81.2

X = 44 X² = 480 Y = 33.6 Y² = 227.78 XY = 282.8

What is the y-intercept (a)for this data?