Probability Example Questions

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Consider the following basic Probability Example Questions.

1. A fair dice is rolled. What is the probability of getting the number four?
Solution
$S.S=\{1,2,3,4,5,6\}$
Here, favorable events = 1 (that is 4), and total events = 6
So, $n=6$ , and $r=1$
Using probability formula

$P(4)=\frac{r}{n}=\frac{1}{6}=0.1667$

2. A fair dice is rolled. What is the probability of getting an even number?
Solution
$S.S=\{1,2,3,4,5,6\}$
Here, favorable events = 3 (that are 2, 4, 6), and total events = 6
So, $n=6$ , and $r=3$
Using probability formula

$P(\textrm{even number})=\frac{r}{n}=\frac{3}{6}=0.5$

3. A card is drawn from a pack of 52 cards. What is the probability that the card is a queen?
Solution
Here, favorable events = 4 (because there are 4 queens in total in 52 cards). And, total events = 52 (total number of cards).
So, $n=52$ , and $r=4$
Using probability formula

$P(\textrm{queen})=\frac{r}{n}=\frac{4}{52}=0.077$