CBSE 2022 · Region 1 · Set 1 · Q4 · 2 marks
Let A and B be two events such that $\displaystyle \mathrm{P}(\mathrm{A})=\frac{5}{8}, \mathrm{P}(\mathrm{B})=\frac{1}{2}$ and $\displaystyle \mathrm{P}(\mathrm{A} / \mathrm{B})=\frac{3}{4}$. Find the value of $\displaystyle \mathrm{P}(\mathrm{B} / \mathrm{A})$.
Marking-scheme solution
\[\begin{aligned}
& P(A / B)=\frac{P(A \cap B)}{P(B)}=\frac{3}{4} \Rightarrow P(A \cap B)=\frac{3}{8} \\
& P(B / A)=\frac{P(B \cap A)}{P(A)}=\frac{\dfrac{3}{8}}{\dfrac{5}{8}}=\frac{3}{5}
\end{aligned}
\]
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CBSE Class 12 Mathematics past-paper question from the 2022board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.