Question

The attendance report of a class for 150 days is as follows:

$\begin{array}{cc}\text{Student}& \text{Attendance}\\ 1& 146\\ 2& 142\\ 3& 147\\ 4& 149\\ 5& 146\\ 6& 145\\ 7& 147\\ 8& 146\\ 9& 145\\ 10& 150\\ 11& 143\\ 12& 145\\ 13& 144\\ 14& 142\\ 15& 148\end{array}$

What is the probability that a student has 98% or more attendance?

• A. $\frac{1}{2}$
• B. $\frac{1}{3}$
• C. $\frac{1}{4}$
• D. $\frac{1}{5}$

Answer 1

The correct option is B

$\frac{1}{3}$

98 percentage of 150 $=\frac{98}{100}\times 150=147$

We know, for an event E
$\text{P(E)}=\frac{\text{Number of trials in which the event happened}}{\text{Total number of trials}}$

Here, the event is a student having an attendance of 98% or more.
From the given table, we see that students 3, 4, 7, 10 and 15 have an attendance of 98% or more.
Hence,
Number of students having an attendance of 98% or more = 5
Total number of students = 15
$\therefore \text{Required probability}=\frac{5}{15}=\frac{1}{3}$