Question

P(A)=7/20,P(B)=3/5,P(A∩B)=21/100 ,P(A∪B)=?

Answer 1

$P(A U B) = P(A) +P(B) - P(AB) \\ \\ = \frac{7}{20} +\frac{3}{5} - \frac{21}{100} \\ \\ = \frac{35}{100} +\frac{60}{100} - \frac{21}{100} \\ \\ =\frac{74}{100} \\ \\ =\frac{37}{50}$