Question

check if it is in proportion
5.2 : 3.9 :: 3 : 4​

Answer 1

$\: \: \: \: \: \: \: \: \: \: \: 5.2:3.9::3:4 \\ \\ if \: it \: is \: in \: proportion \: then \: the \: product \:of \\ mean \: would \: be \: equal \: to \: product \: of \: extreme \\ \\ therefore \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \:solving \: means' \: products \: as \: 3.9 \times3 = 11.7 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \:solving \: extremes' product \: as \: 5.2 \times 4 = 20.8 \\ \\ \\ \\ as \: here \: the \: products \: aren't \: equal \\ \\ \\ \\ \\ \\ hence \: proved \: that \: the \: given \: numbers \: aren't \: in \: proportion$