Answer: a) 0.28 b) 0.13
Step-by-step explanation: Fred is happy = 0.8
Fred is not happy = 0.2
John is happy = 0.35
John is not happy = 0.65
a) Fred and John are happy → and is x
0.8 x 0.35 = 0.28
b) Neither Fred nor John is happy → both not happy → Fred is not happy and John is not happy
0.2 x 0.65 = 0.13