1
P(V|A) is not 0.95. It is opposite:
P(A|V)=0.95
From the text we can also conclude, that
P(A|∼V)=0.1
P(B|V)=0.9
P(B|∼V)=0.05
P(V)=0.01
P(∼V)=0.99
What you need to calculate and compare is P(V|A) and P(V|B)
P(V∩A)=P(A)⋅P(V|A)⇒P(V|A)=P(V∩A)P(A)
P(V∩A) means, that Joe has a virus and it is detected, so
P(V∩A)=P(V)⋅P(A|V)=0.01⋅0.95=0.0095
P(A) is sum of two options: "Joe has virus and it is detected" and "Joe has no virus, but it was mistakenly detected", therefore:
P(A)=P(V)⋅P(A|V)+P(∼V)⋅P(A|∼V)=0.01⋅0.95+0.99⋅0.1=0.1085
Surface area of cubic= 2( lb+bh+hl)
Length= 18 cm
Width= 5 cm
Height= 2cm
