First slide

Theorems of probability

Question

Ten boys are arranged at random along a circle. The probability of arranging them so that two specified boys of those ten must come together is

Easy

A

$\frac{1}{9}$
B

$\frac{2}{9}$
C

$\frac{1}{3}$
D

$\frac{5}{9}$

Solution

$n (S) = (10 - 1)! = 9!$
$n (E) = 8! \times 2!$

$[\begin{matrix} 2 Boys - 1 unit \\ 8 Boys - 8 units \end{matrix}]$

The probability of arranging them so that two specified boys of those ten must come together is $= P (E) = \frac{8! \times 2!}{9!} = \frac{2}{9}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App