Question
If the third proportion of 8 and 16 is “0.5k”, then
find the value of (k − 4) : (k + 14).Solution
Third proportion of two numbers ‘a’ and ‘b’ is (b²/a). 
 So, 0.5k = (16²/8) = 32 
 Or, 'k' = 64 
 Required value = (64 - 4) : (64 + 14) = 60 : 78 = 10 : 13
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