a and d are called the extremes, b and c are called the means.
a, b, c and d are called first proportion, second proportion, third proportion and fourth proportion respectively.![]()
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27 : 39 = 36 : x

Ans: x = 52
Continued Proportion:
If a, b, c are said to be continued proportion, then a : b = b : c
b2 = a x c
