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Date November Example question Marks available 4 Reference code EXN.1.SL.TZ0.12
Level Standard Level Paper Paper 1 Time zone Time zone 0
Command term Find Question number 12 Adapted from N/A

Question

A disc is divided into 9 sectors, number 1 to 9. The angles at the centre of each of the sectors un form an arithmetic sequence, with u1 being the largest angle.

It is given that u9=13u1.

Write down the value of Σi=19ui.

[1]
a.

Find the value of u1.

[4]
b.

A game is played in which the arrow attached to the centre of the disc is spun and the sector in which the arrow stops is noted. If the arrow stops in sector 1 the player wins 10 points, otherwise they lose 2 points.

Let X be the number of points won

Find E(X).

[2]
c.

Markscheme

* This sample question was produced by experienced DP mathematics senior examiners to aid teachers in preparing for external assessment in the new MAA course. There may be minor differences in formatting compared to formal exam papers.

 

360°      A1 

  

[1 mark]

a.

EITHER

360=92u1+u9        M1

360=92u1+13u1=6u1        M1A1

 

OR

360=922u1+8d        M1

u9=13u1=u1+8du1=-12d        M1

Substitute this value 360=922u1-8×u112  =92×43u1=6u1        A1

 

THEN

u1=60°        A1

  

[4 marks]

b.

E(X)=10×60360-2×300360=0        M1A1

  

[2 marks]

c.

Examiners report

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

Syllabus sections

Topic 1—Number and algebra » SL 1.2—Arithmetic sequences and series
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Topic 4—Statistics and probability » SL 4.7—Discrete random variables
Topic 1—Number and algebra
Topic 4—Statistics and probability

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