There are two stages:1. A coin is chosen at random.So,P(blue coin)=21​P(red coin)=21​2. The chosen coin is tossed.We want P( Head ).Use the law of total probability:P(Head)=P(Head∣blue)⋅P(blue)+P(Head∣red)⋅P(red)Substitute the values:P(Head)=0.99⋅21​+0.01⋅21​P(Head)=20.99+0.01​=21.00​=0.5Answer:0.5