The intercept of the eyeballed regression line is approximately 70.
The regression line is a line that best fits the data points in the scatterplot.
To eyeball-estimate the regression line, I look at the overall pattern of the data points and try to draw a line that passes through as many points as possible, with an equal number of points above and below the line.
In the given scatterplot, the data points have a positive correlation, meaning that as the child's score increases, the adult's IQ also tends to increase.
The regression line should therefore have a positive slope.
Estimate of the intercept
The intercept of the regression line is the point where the line crosses the y-axis.
In other words, it is the predicted value of the adult's IQ when the child's score is zero.
From the eyeballed regression line, I estimate that the intercept is approximately 70.
This is because the line crosses the y-axis at a point that is approximately 70 units above the origin.