book states

thats basically 6540 micro farads, but that answer was deemed incorrect when I submitted my assignment. so my question is where did i go wrong?

 

Your value for R of 288Ω is incorrect because you based this on the RMS source voltage - rather than the estimated DC load voltage.

The approximate DC load voltage will be Vm-Vr/2, where Vr is the peak-to-peak ripple.

 

so the value for Rload would be

Rload = ((Vm-Vr)/2)^2/50
= ((169.7-1.5)/2)^2/50
=141.46ohms

is this correct?

 

Not quite - I wrote Vm-Vr/2 not (Vm-Vr)/2

So Vdc would be 120*√2-0.75=168.96V

 

Rload=(168.96^2)/50
Rload=570.95ohms

so

=(120(1.414))/(50)(570.95)(1.5)
=169.7/42821.25
=.00396297
=3962microF

thats really not even close to any answers on there

 

This was my approach ....

 

thank you for your help