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2.3 Probability

2.3 Probability

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Question 129

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]
Markscheme

2.3 Probability Questions

  1. A Level
  2. /Maths
  3. /2.3 Probability

200 exam-style questions on OCR (MEI) A Level Maths 2.3 Probability, covering 2.3.1 Calculate the probability of an event, 2.3.2 Complementary events, 2.3.3 Expected frequency of an event, 2.3.4 Diagrams to calculate probabilities, 2.3.5 Mutually exclusive and independent events, 2.3.6 Add probabilities for mutually exclusive events, 2.3.7 Multiply probabilities for independent events, 2.3.8 Mutually exclusive and independent events (notation) (A-level only), 2.3.9 Venn diagrams for probabilities (A-level only), 2.3.10 Conditional probabilities (A-level only), and 2.3.11 Independence via conditional probability (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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