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2.3.3 Conditional probability (A-level only)

2.3.3 Conditional probability (A-level only)

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Question 87

A botanical research station is studying a population of 200 rare plant specimens. The specimens are classified by their height, hhh cm, and their species type (Alpha or Beta), as shown in the table below.

Height, hhh cmSpecies AlphaSpecies Beta
h<15h < 15h<151832
15≤h<4015 \le h < 4015≤h<403545
40≤h40 \le h40≤h2743

One specimen is selected at random from the research station.

a.

Find the probability that the specimen is Species Alpha.

[2]
b.

Given that the specimen has a height of less than 15 cm, find the probability that it is Species Beta.

[2]
c.

Given that the specimen has a height of less than 40 cm, find the probability that it is Species Beta.

[3]
d.

State, with a reason, whether or not the event 'Species Beta' is independent of the event 'height is less than 15 cm'.

[2]
Markscheme

2.3.3 Conditional probability (A-level only) Questions

  1. A Level
  2. /Maths
  3. /2.3.3 Conditional probability (A-level only)

116 exam-style questions on OCR A Level Maths 2.3.3 Conditional probability (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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