A coin is tossed four times, and $X$ is the number of heads. What is $P(X = 1)$ ?

\frac{1}{16}

Correct answerYour answer

\frac{1}{5}

Correct answerYour answer

\frac{1}{4}

Correct answerYour answer

\frac{1}{2}

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer C

Correct answer: C

There are $2^{4} = 16$ equally likely outcomes.
Exactly one head: $HTTT, THTT, TTHT, TTTH$ , 4 outcomes, so $\frac{4}{16} = \frac{1}{4}$ .

Worth noting

$\frac{1}{5}$ treats the 5 possible values 0 to 4 as equally likely; they are not.

Ten questions from Random Variables, Expectation & Variance, at your own pace.

Ten questions from Random Variables, Expectation & Variance, at your own pace.

A coin is tossed four times, and XXX is the number of heads. What is P(X=1)P(X = 1)P(X=1)?