B is false, since by the inclusion/exclusion principle,

By independence, we have
, which is zero if either of
or
is 0, which isn't guaranteed.
Hope this helps you with your questions.
A because 40% of 3500 is 40%
Risk - 5 = 16. It is just mathematical language.
We have to multiply those measurements to get the area of a living room
10.6 ft * 9.28 ft
98.368 ft^2