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Conditional Probability

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Question 115

A survey of 80 software developers is conducted to investigate the programming languages they use.

It is found that, of the 80 developers:

  • 50 developers use Python
  • 32 developers use Java
  • 20 developers use both Python and Java
a.

A developer is selected at random from the 80 surveyed. Determine whether the event 'the developer uses Python' and the event 'the developer uses Java' are independent.

[2]
b.

In a cybersecurity firm, the following probabilities are known for a specific server over a given interval:

  • the probability of a Denial of Service (DoS) attack is P(A)=0.15P(A) = 0.15P(A)=0.15
  • the probability of a Brute Force attempt is P(B)=0.28P(B) = 0.28P(B)=0.28
  • the probability of a DoS attack occurring given that a Brute Force attempt has occurred is P(A∣B)=0.25P(A|B) = 0.25P(A∣B)=0.25

Calculate the probability that the server experiences a DoS attack, a Brute Force attempt, or both.

[3]

Conditional Probability Questions

  1. A Level
  2. /Maths
  3. /Conditional Probability

Practise Edexcel A Level Maths Conditional Probability with exam-style questions for A Level Maths. 152 questions, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.

Question bank