Question and Answers Forum

All Questions      Topic List

Permutation and Combination Questions

Previous in All Question      Next in All Question      

Previous in Permutation and Combination      Next in Permutation and Combination      

Question Number 136448 by adhigenz last updated on 22/Mar/21

$$\mathrm{Mr}.\mathrm{A}\mathrm{wants}\mathrm{to}\mathrm{deliver}7\mathrm{letters}\mathrm{to}\mathrm{his}7\mathrm{friends}\mathrm{so}\mathrm{that}\mathrm{each}\mathrm{gets}1\mathrm{letter}.$$$$\mathrm{All}\mathrm{of}\mathrm{the}\mathrm{letters}\mathrm{are}\mathrm{written}\mathrm{of}\mathrm{the}\mathrm{addresses}\mathrm{of}\mathrm{his}7\mathrm{friends}.\mathrm{Find}\mathrm{the}\mathrm{probbility}\mathrm{that},$$$$3\mathrm{of}\mathrm{his}\mathrm{friends}\mathrm{receive}\mathrm{the}\mathrm{correct}\mathrm{letters}\mathrm{and}\mathrm{the}\mathrm{remaining}4\mathrm{receive}\mathrm{the}\mathrm{wrong}\mathrm{ones}.$$

Answered by mr W last updated on 22/Mar/21

$$p=\frac{P_3^7\times !4}{7!}=\frac{!4}{4!}=\frac{9}{24}=\frac{3}{8}=37.5\mathrm{\%}$$

Commented by john_santu last updated on 23/Mar/21

$$ithinkit\frac{1}{16}sir$$

Commented by john_santu last updated on 23/Mar/21

$$p=\frac{C_3^7\times !4}{7!}=\frac{7!.(!4)}{4!.3!.7!}=\frac{9}{24\times 6}=\frac{1}{16}$$

Commented by mr W last updated on 23/Mar/21

$$yes!$$

Terms of Service

Privacy Policy

Contact: info@tinkutara.com