In an examination, 40% of students failed in Hindi and 50% failed in English. If 21% failed in both subjects, what percentage passed in Hindi?

Introduction / Context:
The question asks only for the percentage who passed Hindi, independent of their English outcome. That depends solely on the failure rate in Hindi.

Given Data / Assumptions:

• Failed Hindi = 40% of students.
• Failed English = 50% of students.
• Failed both = 21% of students (not actually needed to answer the asked part).

Concept / Approach:
Percentage passed in Hindi = 100% − percentage failed in Hindi. Overlaps with English do not affect the Hindi pass count, as ”passed Hindi” includes those who may have failed English.

Step-by-Step Solution:

Verification / Alternative check:
Construct a Venn diagram: regardless of the English circle, the complement of the Hindi-fail region is 60%.

Why Other Options Are Wrong:
40% and 31% relate to confusions with English failure or double-counting both; 55% uses arbitrary adjustments; 79% incorrectly adds/subtracts the overlap.

Common Pitfalls:
Overcomplicating with unnecessary inclusion–exclusion. The English results do not matter for ”passed Hindi”.

Final Answer:
60%