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2.3.3 Conditional probability (A-level only)

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Question 80

The frequencies for 80 deep-sea submersible dives are recorded in a Venn diagram. The events are defined as:

CCC: Dive records a Colossal Squid

AAA: Dive records an Anglerfish

VVV: Dive records a Viperfish

In the section of circle CCC only, there is the number 18. In the intersection of CCC and AAA, there is the number 10. In the section of circle AAA only, there is the number 14. Separate from circles CCC and AAA, there is a third circle VVV, which does not overlap with CCC or AAA. Inside circle VVV, there is the number 24. Outside all three circles but inside the rectangle (the universal set ξ\xiξ), there is the number 14.

a.

Write down two of these events that are mutually exclusive. Give a reason for your answer.

[2]
b.

Determine whether or not CCC and AAA are independent events.

[2]
c.

One dive is chosen at random from the log. Find the probability that it:

records a Viperfish,

[1]
d.

records both a Colossal Squid and an Anglerfish.

[1]
e.

Given that a dive records a Colossal Squid, find the probability that it also records an Anglerfish.

[2]

2.3.3 Conditional probability (A-level only) Questions

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