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Date November 2009 Marks available 3 Reference code 09N.1.sl.TZ0.14
Level SL only Paper 1 Time zone TZ0
Command term Find Question number 14 Adapted from N/A

Question

A class consists of students studying Spanish or French or both. Fifteen students study Spanish and twelve study French.

The probability that a student studies French given that she studies Spanish is 715.

Draw a Venn diagram in the space below to illustrate this information.

[3]
a.

Find the probability that a student studies Spanish given that she studies one language only.

[3]
b.

Markscheme

     (A1)(A1)(A1)     (C3)


Note: Award (A1) for a labeled Venn diagram with appropriate sets.

(A1) for 7, (A1) for 8 and 5.

 

[3 marks]

a.

P (Spanish / one language only)=820820+520     (M1)(A1)(ft)


Note: Award (M1) for substituted conditional probability formula, (A1) for correct substitution. Follow through from their Venn diagram.


=813(0.615, 61.5%)     (A1)(ft)

OR

P (Spanish / one language only)=88+5     (A1)(ft)(M1)


Note: Award (A1) for their correct numerator, (M1) for correct recognition of regions. Follow through from their Venn diagram.


=813(0.615, 61.5%)     (A1)(ft)     (C3)

[3 marks]

b.

Examiners report

Part (a) was done well.

a.

Very few were able to answer (b).

b.

Syllabus sections

Topic 3 - Logic, sets and probability » 3.5 » Venn diagrams and simple applications.
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