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Suppose you draw a card from a well-shuffled deck (recall that there are 52 cards and 4 suits, each with 13 cards). Event A occurs if it is a black card. Event B occurs if it is an Ace.

Which of the following is true?

P(A|B) < P(B|A)

❌

P(A|B) = P(B|A)

❌

None of the options is correct

P(B|A) P(B)

P(A|B) = P(A)

Imagine you are organizing a community fair with various activities. The probability of having a food stall at the fair is 0.3 and the probability of having a live music performance is 0.6. Having a food stall at the fair and having a live music performance are independent events.

What is the probability of not having a food stall and not having live music at the fair.

None in the list

0.28

0.7

0.18

0.4

A technology company wants to understand the variation in weekly screen time for smartphone users. They randomly select 1,500 users and record their weekly screen time.

The key parameter of interest most likely is:

The variance of weekly screen time among the surveyed users

❌

The number of adults surveyed

❌

None of the options is correct

❌

The variance of weekly screen time for all smartphone users

✅

The amount of screen time of the surveyed users

❌

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A conditional probability:

is the extent to which all the data values group around a typical or central value.

is the pattern of the distribution of values from the lowest value to the highest value.

is the probability that one event is not affected by the other event.

is the probability of one event, given that another event has occurred.

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Consider an experiment that consists in tossing a fair coin four times. What is the probability that we obtain four heads or that we obtain at least one head?

between 0 and 0.1

❌

between 0.9 and 1

✅

None of the options is correct.

0.5

0.25

Two mutually exclusive events:

Always occur together

Cannot occur together

Can sometimes occur together

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If events A and B are mutually exclusive, then:

P(A|B) = P(A)

P(A or B) = P(A) + P(B)

P(A and B) = P(A)xP(B)

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In a scientific laboratory, 85% of the experiments are related to biology, while the remaining 15% are related to chemistry. Suppose that the probability of a laboratory assistant accurately documenting the experiment does not depend on the experiment's type. However, whenever an experiment is documented, the laboratory assistants correctly record the experiment's field in 80% of the cases and mistakenly label it as a different field in 20% of the cases.

What is the probability that a lab assistant labels an experiment as a biology experiment?

0.64

Other value.

0.83

0.58

0.71

100%

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A marketing manager calculates the percentage of survey respondents who prefer Product A over Product B.

This is a:

Descriptive Analysis

✅