Foundation November 2022 Paper 3 Q21

21 The scatter graph shows the height and mass of some dogs.

(a) The scatter graph shows positive correlation.

Describe the relationship between the height and mass of the dogs. [1 mark]

(b) Use a line of best fit to estimate the mass of a dog with height 48 cm [2 marks]

Mark scheme (a)

Answer	Mark	Comments
Valid description	B1	eg as height increases so does mass or as mass decreases so does height

Ignore incorrect or irrelevant statements alongside correct statements, unless contradictory
As one increases so does the other	B1
It is usually heavier the taller it is	B1
As height increases the weight increases	B1
They are directly proportional (condone)	B1
It is positive correlation because the taller the dogs the heavier the dogs	B1
The taller they are the more they weigh	B1
Taller dogs are heavier	B1
The tallest dogs have more mass than the shorter dogs	B1
The shortest dogs have a lower mass	B1
Mass and height both increase at the same time (condone)	B1
The height and mass of the dogs increase at the same rate (condone)	B1
A tall dog is heavy	B0
The bigger they are the more they weigh (height is not implied from bigger)	B0
It is heavier as it grows (height is not implied from growth)	B0
It is positive correlation	B0

Mark scheme (b)

Answer	Mark	Comments
Straight line passing through (36, [9, 13]) and (62, [30, 34])	B1	accept intention to draw a straight line ignore anything outside (36, [9, 13]) and (62, [30, 34])
Correct reading \(\pm\dfrac{1}{2}\) square for their straight line	B1ft	ft their line with positive gradient ignore any working lines on their graph

No line of best fit	B0B0
Short straight line not passing through (36, [9, 13]) and (62, [30, 34]) with positive gradient and correct reading \(\pm\dfrac{1}{2}\) square for their line	B0B1ft
Two lines of best fit, mark the line that leads to their answer
Two lines of best fit, no answer, apply the usual rules of choice