Exercise 2.3

 (6) Find the number of garlands that can be made using 6 different coloured flowers taken 4 at a time

no.of garlands can be made using 6 different coloured flowers taken 4 at a time $=\frac{{}^{n}p_r}{2r}=\frac{{}^{6}P_4}{2\left(4\right)}$$=\frac{6\times 5\times 4\times 3}{2\left(4\right)}=45$