Fourth proportion of 1/3,2/5and8.4

1.	Fourth proportion of 1/3,2/5and8.4
Answer» 1/3 : 2/5 :: 8/4 : ? let the fourth no. be = x Product of means = Product of extremes $\implies$ 1/3 * x = 2/5 * 8/4 $\longrightarrow$ ( 1+3x) / 3 = (8+40)/20 $\longrightarrow$ 3x +1 = 3* 48/20 $\longrightarrow$ 3x + 1 = 144/20 $\longrightarrow$ 3x = 1 + 144/20 $\longrightarrow$ 3x = 164 /20 $\longrightarrow$ 3x = 41/5 $\implies$ X = 41/15

Answer»

1/3 : 2/5 :: 8/4 : ? let the fourth no. be = x

$\implies$ 1/3 * x = 2/5 * 8/4

$\longrightarrow$ ( 1+3x) / 3 = (8+40)/20

$\longrightarrow$ 3x +1 = 3* 48/20

$\longrightarrow$ 3x + 1 = 144/20

$\longrightarrow$ 3x = 1 + 144/20

$\longrightarrow$ 3x = 164 /20

$\longrightarrow$ 3x = 41/5