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Date May Example question Marks available 9 Reference code EXM.1.SL.TZ0.9
Level Standard Level Paper Paper 1 Time zone Time zone 0
Command term Test Question number 9 Adapted from N/A

Question

Six coins are tossed simultaneously 320 times, with the following results.

At the 5% level of significance, test the hypothesis that all the coins are fair.

Markscheme

Let H0 be the hypothesis that all coins are fair,      (C1)

and let H1 be the hypothesis that not all coins are fair.     (C1)

Let T be the number of tails obtained, T  is binomially distributed.               (M1)

        (A3)

Notes:  Award (A2) if one entry on the third row is incorrect. Award (A1) if two entries on the third row are incorrect. Award (A0) if three or more entries on the third row are incorrect.

χ calc 2 = ( 5 5 ) 2 5 + ( 40 30 ) 2 30 + ( 86 75 ) 2 75 + ( 89 100 ) 2 100 + ( 67 75 ) 2 75 + ( 29 30 ) 2 30 + ( 4 5 ) 2 5

= 7.24           (A1) 

Also  χ 0.05 , 6 2 = 12.592           (A1) 

Since 7.24 < 12.592, H0 cannot be rejected.         (R1)

[9 marks]

Examiners report

[N/A]

Syllabus sections

Topic 4—Statistics and probability » SL 4.8—Binomial distribution
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