P(A B) = 0.12 and P(B A) = 0.3. What is P(A)?

Conditional Probability & Bayes' Theorem · Question 33 of 125

Question 33

EasyOriginal question

$P(A \cap B) = 0.12$ and $P(B \mid A) = 0.3$ . What is $P(A)$ ?

0.036

Correct answerYour answer

0.18

Correct answerYour answer

0.4

Correct answerYour answer

0.42

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer C

Correct answer: C

$P(A \cap B) = P(A)\,P(B \mid A)$ , so $P(A) = \frac{P(A \cap B)}{P(B \mid A)}$ .
$\frac{0.12}{0.3} = 0.4$ .

Worth noting

0.036 multiplies, $0.12 \times 0.3$ ; to undo the theorem's product, divide.

Ten questions from Conditional Probability & Bayes' Theorem, at your own pace.

Ten questions from Conditional Probability & Bayes' Theorem, at your own pace.