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Date May 2014 Marks available 2 Reference code 14M.1.sl.TZ2.12
Level SL only Paper 1 Time zone TZ2
Command term Find Question number 12 Adapted from N/A

Question

A survey investigated the relationship between the number of cleaners, n, and the amount of time, t, it takes them to clean a school.


Use your graphic display calculator to write down the equation of the regression line t on n.

[2]
a.

Write down the value of the Pearson’s product–moment correlation coefficient, r.

[2]
b.

Use your regression equation to find the amount of time 4 cleaners take to clean the school.

[2]
c.

Markscheme

t=20.1n+205

t=(20.1046)n+(204.755)     (A1)(A1)     (C2)

 

Notes: Award (A1) for 20.1 and 205 seen,

     (A1) for an equation involving t and n.

 

[2 marks]

a.

0.941(0.941366)     (A2)     (C2)

 

Notes: Award (A0)(A1) for +0.941.

 

[2 marks]

b.

20.1046×4+204.755     (M1)

 

Note: Award (M1) for substitution into their regression equation.

 

124 (minutes) (124.337)     (A1)(ft)     (C2)

 

Notes: Follow through from their regression equation found in part (a). Accept 125 (minutes) (124.6).

 

[2 marks]

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Topic 4 - Statistical applications » 4.3 » The regression line for y on x.
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