Question

A boy was late for school $5$ times in the previous $30$ school days. If tomorrow
is a school day. Calculate the probability that he will arrive late.

Answer 1

Hint: Probability of any given event is equal to the ratio of the favourable outcomes with the total number of the outcomes. Probability is the state of being probable and the extent to which something is likely to happen in the particular situations.

Complete step-by-step answer:
Given that: -
The number of school days here are given $30$ days
$S = \{ 1,2,....,29,30\} $
Therefore, $n(s) = 30$
Let A be an event that the boy was late for school $5$ times in the $30$ days of school.
$n(A) = 5$
Therefore, the required probability of the boy being late $ = P(A)$
   $P(A) = $ Total number of the favourable outcomes / Total number of the outcomes
$\begin{array}{l}
\therefore P(A) = \dfrac{{n(A)}}{{n(S)}}\\
\therefore P(A) = \dfrac{5}{{30}}
\end{array}$
$\therefore P(A) = \dfrac{1}{6}$
Hence, the probability of the boy being late is, $\therefore P(A) = \dfrac{1}{6}$ is the required answer.
Additional information: Questions based on probability are frequently asked and an important part of the quantitative aptitude section of most of the competitive exams.

Note: The probability of any event always lies between the number $0$ and the number $1$. It can never be negative nor the number greater than one. Impossible event is equal to zero, whereas a universal true event’s probability is always one.