Answer
$199~pulses/s$
Work Step by Step
We know that
$f^{\prime}=\frac{f}{\sqrt{1-\frac{v^2}{c^2}}}\sqrt{1-\frac{1}{c^2}[\frac{v-v_1}{1-\frac{vv_1}{c^2}}]^2}$
We plug in the known values to obtain:
$f^{\prime}=\frac{153}{\sqrt{1-(\frac{0.800c}{c})^2}}\sqrt{1-\frac{1}{c^2}[\frac{0.800c-0.950c}{1-\frac{(0.800c)(0.950c)}{c^2}}]^2}$
This simplifies to:
$f^{\prime}=199~pulses/s$
