Question

. (10 points) Based on pre-trial speculation, the probability that a jury returns a guilty verdict in a certain high-profile murder case is thought to be 15% if the defense can discredit the police department, and 80% if they cannot. Veteran court observers believe that the skilled defense attorneys have a 70% chance of convincing the jury that the police either contaminated or planted some evidence. What is the probabiliy that the jury returns a guilty verdict?

Answer 1

34.5% probability that the jury returns a guilty verdict

Explanation:

We have these following probabilities:

If the police can discredit the police department, 15% probability of a guilty verdict.

70% probability of the police department being discredited by the defense.

If the police can discredit the police department, 80% probability of a guilty verdict.

100 - 70 = 30% probability of the defense not discrediting the police.

What is the probability that the jury returns a guilty verdict?

15% of 70% and 80% of 30%. So

p = 0.15*0.7 + 0.8*0.3 = 0.345

34.5% probability that the jury returns a guilty verdict