A researcher is testing the effectiveness of a political video. She has randomly sampled 120 people to test the video. For each person, there is 50% chance the person will be Democrat and 50% chance the person will be Republican. Republicans have 75% chance of reacting to the video and Democrats have 25% chance of reacting to the video.
What is the expected value and variance of the number of people in the $ 120 $ who respond to the video?
Expected value is straight forward: $ (120*0.5*0.25)+(120*0.5*0.75)=60 $
How do I go about finding the variance though? Is it $ 0 $?