We solve previous statistics exercises
1. Representing the table with a scatterplot Mi(xi;yi) in a perpendicular coordinate system with origin o' (30;11) and a scale of 1 cm for every 5 years on the axis of abscissa and 2 cm on the axis of ordinates.
2. a) Assigning the coordinates of point G as the center of the scatterplot.
We have point G (x̄;ȳ), where:
And from it: G(50;13)
b) Representation of point G in the previous chart. (represented in the diagram above)
3. Finding the equation of the least squares regression line: y=ax+b, a and b are given rounded to 10-2.
The regression line equation has the form y=ax+b, where:
To calculate a, we use the following table:
And we have: b= ȳ-ax̄ =13-0.06(50)=10
4) Plot this line in the previous coordinate system. (represented in the diagram above)
5) We have: The man is 70 years old then: x=70
When substituting in the equation of a straight line, we find:
Since 14.2 ≠ 15.2 Therefore, this is unreasonable according to this modification.