A coin is tossed three times and $E$ is the event 'at least two heads'. What is $E'$ ?

At most two headsCorrect answerYour answerExactly one headCorrect answerYour answerAt least two tailsCorrect answerYour answerAt most one headCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer D

Correct answer: D

$E'$ is every outcome not in $E$ : fewer than two heads, that is 0 or 1 head.
So $E'$ is 'at most one head': $\{TTT, HTT, THT, TTH\}$ .

Worth noting

'At least two tails' is the same event as 'at most one head' in three tosses, but 'exactly one head' leaves out $TTT$ .

Concept: The complement of an event
Typical timeTypical: 90 s
Your timeYours: —

The rule this testsThe algebra of events

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Ten questions from Probability, at your own pace.

A coin is tossed three times and EEE is the event 'at least two heads'. What is E′E'E′?

Explanation

A coin is tossed three times and $E$ is the event 'at least two heads'. What is $E'$ ?