RRB Technician Grade I 13 March 2026 Paper

Concept:The problem uses the law of total probability combined with complementary events to find the probability of answering the second question incorrectly.Explanation:Let Q1 and Q2 represent the first and second questions respectively.Given: $P(\text{Q1 correct}) = \frac{1}{5}$.So, $P(\text{Q1 incorrect}) = 1 - \frac{1}{5} = \frac{4}{5}$.If Q1 is correct, $P(\text{Q2 correct}) = \frac{5}{6}$, so $P(\text{Q2 incorrect}) = 1 - \frac{5}{6} = \frac{1}{6}$.If Q1 is incorrect, $P(\text{Q2 correct}) = \frac{1}{4}$, so $P(\text{Q2 incorrect}) = 1 - \frac{1}{4} = \frac{3}{4}$.Now, apply the law of total probability:$P(\text{Q2 incorrect}) = P(\text{Q1 correct}) \times P(\text{Q2 incorrect} \mid \text{Q1 correct}) + P(\text{Q1 incorrect}) \times P(\text{Q2 incorrect} \mid \text{Q1 incorrect})$.Substituting the values:$P(\text{Q2 incorrect}) = \left(\frac{1}{5} \times \frac{1}{6}\right) + \left(\frac{4}{5} \times \frac{3}{4}\right)$.This simplifies to $\frac{1}{30} + \frac{3}{5}$.Writing with a common denominator: $\frac{1}{30} + \frac{18}{30} = \frac{19}{30}$.Answer:The probability that Chris will answer the second question incorrectly is $\frac{19}{30}$, which matches option A.