# Ravens

The tale of the Seven Ravens were seven brothers, each of whom was born exactly 2.5 years after the previous one. When the eldest of the brothers was 2-times older than the youngest, mother all curse. How old was seven ravens brothers when their mother cursed?

Result

k1 (youngest) =  15
k2 =  17.5
k3 =  20
k4 =  22.5
k5 =  25
k6 =  27.5
k7 (oldest) =  30

#### Solution:

$\dfrac{ k_1}{ k_7} = \dfrac{ x }{ 6\cdot 2.5+x } = \dfrac{ 1} { 2 } \ \\ 2 x = 6 \cdot 2.5 + x \ \\ x = \dfrac{ 6\cdot 2.5}{ 2-1} = 15 \ \\ \ \\ k_1 = 15$
$k_2 = k_1 + 2.5 = 17.5$
$k_3 = k_2 + 2.5 = 20$
$k_4 = k_3 + 2.5 = 22.5$
$k_5 = k_4 + 2.5 = 25$
$k_6 = k_5 + 2.5 = 27.5$
$k_7 = k_6 + 2.5 = 30$

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