A club has 20 members, 12 boys and 8 girls. Two of the members are chosen at random. What is the probability that a boy and a girl are chosen?
+118723 $$\frac{12*8}{20C2}$$
$${\frac{\left({\mathtt{12}}{\mathtt{\,\times\,}}{\mathtt{8}}\right)}{{\left({\frac{{\mathtt{20}}{!}}{{\mathtt{2}}{!}{\mathtt{\,\times\,}}({\mathtt{20}}{\mathtt{\,-\,}}{\mathtt{2}}){!}}}\right)}}} = {\frac{{\mathtt{48}}}{{\mathtt{95}}}} = {\mathtt{0.505\: \!263\: \!157\: \!894\: \!736\: \!8}}$$
0.505 maybe 
+118723 $$\frac{12*8}{20C2}$$
$${\frac{\left({\mathtt{12}}{\mathtt{\,\times\,}}{\mathtt{8}}\right)}{{\left({\frac{{\mathtt{20}}{!}}{{\mathtt{2}}{!}{\mathtt{\,\times\,}}({\mathtt{20}}{\mathtt{\,-\,}}{\mathtt{2}}){!}}}\right)}}} = {\frac{{\mathtt{48}}}{{\mathtt{95}}}} = {\mathtt{0.505\: \!263\: \!157\: \!894\: \!736\: \!8}}$$
0.505 maybe
