Question

If the probability of A to fails in the examination is $\frac{1}{5}$ and that of B is $\frac{3}{10},$ then probability that either A or B fails is

• A. $\frac{38}{100}$
• B. $\frac{50}{100}$
• C. $\frac{11}{25}$
• D. $\frac{3}{50}$

Answer 1

The correct option is C $\frac{11}{25}$

probability that either A or B = P (A fails) + P(B fails) - P(both fails)
A = A fails
B = B fails
considering A and B independent events, P(AB) = P(A) * P(B)
probability that either A or B $=\frac{1}{5}+\frac{3}{10}-\frac{3}{50}=\frac{11}{25}$