diff --git a/p4_tracking/inference.py b/p4_tracking/inference.py
index 0e39a0a..0ee7911 100644
--- a/p4_tracking/inference.py
+++ b/p4_tracking/inference.py
@@ -478,18 +478,17 @@ class JointParticleFilter:
 
         distribution, samples = [], []
         for particle in self.particles:
-            weight = 1 # weight is likelihood over whole particle
+            weight = 1.0 # weight is likelihood over whole particle
+            particle = tuple(particle)
             for ghostIndex in range(self.numGhosts):
-                noisyDistance = noisyDistances[ghostIndex]
-                emissionModel = emissionModels[ghostIndex]
-                if noisyDistance is None:
+                if noisyDistances[ghostIndex] is None:
                     # Ghost is in jail.
                     particle = self.getParticleWithGhostInJail(particle, ghostIndex)
                 else:
                     # Find probability and update weight.
                     ghostPosition = particle[ghostIndex]
                     trueDistance = util.manhattanDistance(ghostPosition, pacmanPosition)
-                    probability = emissionModel[trueDistance]
+                    probability = emissionModels[ghostIndex][trueDistance]
                     weight = weight * probability
             distribution.append(weight)
             samples.append(particle)
@@ -497,14 +496,17 @@ class JointParticleFilter:
         if not [p for p in distribution if p > 0.0]:
             # All probabilities are zero so we have to reinitialize.
             self.initializeParticles()
-            newParticles = []
             # But then make sure that we move jailed ghosts into jail.
-            for particle in self.particles:
-                for ghostIndex in range(self.numGhosts):
-                    if noisyDistances[ghostIndex] is None:
+            jailedGhostIndices = [i 
+                for i, noisyDistance in enumerate(noisyDistances)
+                if noisyDistance is None]
+            if jailedGhostIndices:
+                newParticles = []
+                for particle in self.particles:
+                    for ghostIndex in jailedGhostIndices:
                         particle = self.getParticleWithGhostInJail(particle, ghostIndex)
-                newParticles.append(particle)
-            self.particles = newParticles
+                    newParticles.append(particle)
+                self.particles = newParticles
         else:
             self.particles = util.nSample(distribution, samples, self.numParticles)
 
@@ -563,12 +565,17 @@ class JointParticleFilter:
         """
         newParticles = []
         for oldParticle in self.particles:
+            prevGhostPositions = oldParticle
             newParticle = list(oldParticle) # A list of ghost positions
             # now loop through and update each entry in newParticle...
-
-            "*** YOUR CODE HERE ***"
-
-            "*** END YOUR CODE HERE ***"
+            for ghostIndex in range(self.numGhosts):
+                ghostPosition = newParticle[ghostIndex]
+                newPosDist = getPositionDistributionForGhost(
+                                setGhostPositions(gameState, prevGhostPositions),
+                                ghostIndex,
+                                self.ghostAgents[ghostIndex])
+                newPos = util.sample(newPosDist)
+                newParticle[ghostIndex] = newPos
             newParticles.append(tuple(newParticle))
         self.particles = newParticles