A source of sound producing wavelength of 50 cm is moving away from stationary observer with $ \large\frac{1}{5}th $ speed of sound. Then, what is the wavelength of sound heard by observer ? - Clay6.com, a Free resource for your JEE, AIPMT and Board Exam preparation

A source of sound producing wavelength of 50 cm is moving away from stationary observer with $ \large\frac{1}{5}th $ speed of sound. Then, what is the wavelength of sound heard by observer ?

$\begin {array} {1 1} (1)\;70\: cm & \quad (2)\;50\: cm \\ (3)\;40\: cm & \quad (4)\;60\: cm \end {array}$