Mathematics - Permutation & Combination Question with Solution | TestHub

$\mathrm{p}:\begin{array}{llllll}0& 0& 0& 0& 0& \text{ place }\\ 5& 4& 3& 2& 1& \text{ ways }\end{array}$ Total no, of ways $=5!=120$ Since all numbers are $>20,000$ $\therefore$ all numbers $2,3,5,7,9$ can come at first place. $\mathrm{q}:\begin{array}{llllll}0& 0& 0& 0& 0& \text{ place }\\ 3& 4& 3& 2& 1& \text{ ways }\end{array}$ Total no. of ways $=3\times 4!=72$ ( $\because 2$ and 9 can not be put at first place) So, $p:q=120:72=5:3$