diff --git a/_psets/12.md b/_psets/12.md
index 6869f16a452c7c9d8cd4a444e6a2e75a8d51854c..ca92e61bfd8628b446078030db2204074ff120e0 100644
--- a/_psets/12.md
+++ b/_psets/12.md
@@ -162,6 +162,7 @@ If an op-amp with a gain–bandwidth product of 10 MHz and an open-loop DC gain
 configured as an inverting amplifier, plot the magnitude and phase of the gain as a function of
 frequency as $$R_\text{out}/R_\text{in}$$ is varied.
 
+
 ## (15.3)
 
 {:.question}
@@ -205,6 +206,13 @@ $$
 Assuming a flat noise power spectrum, what is the coding gain if the entire sequence is used to send
 one bit?
 
+I think the coding gain works out like the SNR I derive in the next problem... but could be wrong.
+
+$$
+10 \log_{10} \left( 2^{88.5} \right) = 266 \si{dB}
+$$
+
+
 ## (15.5)
 
 {:.question}
@@ -291,6 +299,7 @@ $$
 The message 00 10 01 11 00 ($$c_1$$, $$c_2$$) was received from a noisy channel. If it was sent by
 the convolutional encoder in Figure 15.20, what data were transmitted?
 
+
 ## (15.7)
 
 {:.question}