19M.2.SL.TZ1.S_5

pestleMathematicsAASLPaper 219M· sl-4-4-pearsons-scatter-diagrams-eqn-of-y-on-xsource ↗

A jigsaw puzzle consists of many differently shaped pieces that fit together to form a picture.

Jill is doing a 1000-piece jigsaw puzzle. She started by sorting the edge pieces from the interior pieces. Six times she stopped and counted how many of each type she had found. The following table indicates this information.

Jill models the relationship between these variables using the regression equation $y = ax + b$ .

Write down the value of $a$ and of $b$ .

[3]

Use the model to predict how many edge pieces she had found when she had sorted a total of 750 pieces.

[3]

Markscheme / solution

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

valid approach (M1)

eg correct value for $a$ or $b$ (ignore incorrect labels)

$a = 6.92986$ , $b = 8.80769$

$a = 6.93$ , $b = 8.81$ (accept $y = 6.93x + 8.81$ ) A1A1 N3

[3 marks]

valid approach (M1)

eg 750 = $x + y$ , edge + interior = 750

correct working (A1)

eg 750 − $x$ = 6.9298 $x$ + 8.807 , 93.4684

93 (pieces) (accept 94) A1 N3

[3 marks]

Examiners’ report

[N/A]