A coin whose faces are marked 3 and 5 is tossed 4 times. The odds against the sum of the numbers thrown being less than 15 are

$\mathrm{n}\left(\mathrm{S}\right)=2^4 \mathrm{E}=$sum of nos $<15$

$\mathrm{E}\to$$\begin{array}{c}3333\\ 3335\\ 3355\\ 3555\end{array} \overline{) \begin{array}{c}5555 \mathrm{n}\left(\mathrm{E}\right)=1+4\\ \mathrm{P}\left(\mathrm{E}\right)=\frac{5}{16}\end{array}}$

odd against of even $\mathrm{E}=\mathrm{P}\left(\overline{\mathrm{E}}\right) : \mathrm{P}\left(\mathrm{E}\right)$

$=\frac{11}{16} : \frac{5}{16}=11 : 5$