There are four letters and four addressed envelopes. The cha... | MATH - USE OF PERMUTATIONS AND COMBINATIONS IN PROBABILITY | SolveeIt | Solveeit

Today, August 18

Question

There are four letters and four addressed envelopes. The chance that all letters are not dispatched in the right envelope is

A

$\frac { 19 } { 24 }$

B

$\frac { 21 } { 23 }$

C

$\frac { 23 } { 24 }$

D

$\frac { 1 } { 24 }$

Answer

$\frac { 23 } { 24 }$

Explanation

Solution

Required probability is 1 – P

(they go in concerned envelopes) $= 1 - \frac { 1 } { 4 ! } = \frac { 23 } { 24 }$ .