A metal string \( A \) is suspended from a rigid support and its free end is attached to a block of mass \( M \). Second block having mass \( 2M \) is suspended at the bottom of the first block using a string \( B \). The area of cross sections of strings \( A \) and \( B \) are same. The ratio of lengths of strings of \( A \) to \( B \) is \( 2 \) and the ratio of their Young's moduli 
is \( 0.5 \). The ratio of elongations in \( A \) to \( B \) is ________.
