Answer
$1.14$
Work Step by Step
We know that
$f^{\prime}=f(1-\frac{u}{c})$
$\implies \frac{c}{\lambda^{\prime}}=\frac{c}{\lambda}(1-\frac{u}{c})$
This simplifies to:
$\frac{\lambda^{\prime}}{\lambda}=\frac{1}{1-\frac{u}{c}}$
We plug in the known values to obtain:
$\frac{\lambda^{\prime}}{\lambda}=\frac{1}{1-(3.75\times 10^7)(3.00\times 10^8)}$
$\frac{\lambda^{\prime}}{\lambda}=1.14$
