Question

Which one of the following statements expresses a true proportion? A. 2:1 = 1:2 B. 7:9 = 8:9 C. 54:9 = 6:3 D. 3:4 = 9:12

Answer 1

`A:\\2:1=(2)/(1);\ 1:2=(1)/(2)\\\\2:1=1:2\to(2)/(1)=(1)/(2)\to cross\ multiply\\to (2)(2)=(1)(1)\to 4=1\ FALSE!!! :( \\=====================================`


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`C:\\54:9=(54)/(9)=6;\ 6:3=(6)/(3)=2\\\\54:9=6:3\to6=2\ FALSE!!!\ :(\\=====================================`


`D:\\3:4=(3)/(4);\ 9:12=(9)/(12)=(9:3)/(12:3)=(3)/(4)\\\\3:4=9:12\to(3)/(4)=(3)/(4)\ CORRECT\ :)\\=====================================\\\\\huge\boxed{Answer:\boxed{D}}}`