Skip to content
MathsGenie logo
Quick links
Open app

Course home

  1. A Level
  2. Maths AQA
  3. Question bank

2.3.2 Conditional probability (A-level only)

MediumHard
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899
Question 69

A botanical research team is investigating the presence of two rare genetic markers, G1 G_1\,G1​ and G2G_2G2​, in a specific orchid population. The events A A\,A and B B\,B are defined as an orchid having marker G1 G_1\,G1​ and G2 G_2\,G2​ respectively, where

P(A)=p,P(B)=q,P(A∪B)=0.7,P(B∣A)=0.2 P(A) = p, \quad P(B) = q, \quad P(A \cup B) = 0.7, \quad P(B|A) = 0.2 P(A)=p,P(B)=q,P(A∪B)=0.7,P(B∣A)=0.2
a.

Show that

4p+5q=3.5 4p + 5q = 3.5 4p+5q=3.5
[3]
b.

A third genetic marker, G3G_3G3​, is represented by event CCC. It is known that B B\,B and C C\,C are mutually exclusive events such that

P(B∪C)=0.85,P(C)=12p+q P(B \cup C) = 0.85, \quad P(C) = \frac{1}{2}p + q P(B∪C)=0.85,P(C)=21​p+q

(i) Find a second equation in p p\,p and qqq.

(ii) Hence determine the values of p p\,p and qqq.

[5]
c.

Determine whether or not the presence of marker G1 G_1\,G1​ and marker G2 G_2\,G2​ are statistically independent. Justify your answer.

[2]

2.3.2 Conditional probability (A-level only) Questions

  1. A Level
  2. /Maths
  3. /2.3.2 Conditional probability (A-level only)