Question

$X$ is taking subjects Mathematics, Physics, Chemistry in examination. His probability of getting grade $A$ in these subjects are $0.2,0.3,0.5$ respectively. Find the probability that he gets
Grade $A$ in all subjects.

Answer 1

Let $P\left(A\right)$ be a probability of $A$ grade in Maths.

$\therefore$ $P\left(A\right)=0.2$

Let $P\left(B\right)$ be a probability of $A$ grade in Physics.

$\therefore$ $P\left(B\right)=0.3$

Let $P\left(C\right)$ be a probability of $A$ grade in Chemistry.

$\therefore$ $P\left(C\right)=0.5$

Let $P\left(X\right)$ be a probability of $A$ grade in all subjects.

$\Rightarrow$ $P\left(X\right)=P\left(A\right)\times P\left(B\right)\times P\left(C\right)$

$=0.2\times 0.3\times 0.5$

$=0.03$