Suppose that A and B are independent events such thatP(A)=.50 andP(B)=.30 .

Question

Find and P(A U B) and P(A upside down U B) .

Answer 1

P(A or B) but not both
= P(A) + P(B) - P(both A and B)

P(A or B) = P(A U B)

P intersection which is both at once and your upside down U is
P(A)P(B) = .5*.3 = .15

so
P(A U B) = .5 + .3 - .5 = .65

Answer 2

P(A or B)
= P(A) + P(B) - P(both A and B)

P(A or B) = P(A U B)

P intersection which is both at once and your upside down U is
P(A)P(B) = .5*.3 = .15

so
P(A U B) = .5 + .3 - .15 = .65