In a competitive exam with 120 questions, there are three sections: General Knowledge (20 questions), Reasoning (50 questions), and English (50 questions). A candidate answered 70% of General Knowledge, 50% of Reasoning, and 30% of English questions correctly. If the minimum passing score is 60%, how many more questions did the candidate need to answer correctly to pass?

Correct — C. Compare the candidate's total correct with 60% of the whole paper.

GK: 70% of 20 = 14
Reasoning: 50% of 50 = 25
English: 30% of 50 = 15
Total correct: 14 + 25 + 15 = 54

Pass mark: 60% of 120 = 72
Shortfall: 72 − 54 = 18 → option (c)

Why the others are wrong

• (a)
  2 — 2 is GK's surplus, not a shortfall: 14 correct against 60% of 20 = 12. The pass mark applies to the total of 120, not section by section.
• (b)
  15 — 15 is the English count, 30% of 50, and also English's own gap to 60% (30 − 15). The question asks for the gap on the whole paper, 72 − 54.
• (d)
  20 — 20 adds the section gaps and ignores GK's surplus: 5 short in Reasoning (30 − 25) plus 15 in English. GK's 2 extra count towards the total, so 20 − 2 = 18.

An overall percentage is taken on the total, not averaged across sections. Turn each section's percentage into a count, add the counts, and compare with the percentage of the whole.

Averaging 70%, 50% and 30% gives 50%, but the true figure is 54 of 120 = 45%, because the weak 30% section (50 questions) is bigger than the strong 70% one (20 questions).

Key facts

• Overall percentage = total correct ÷ total questions × 100.
• With equal-sized sections, the plain average of the section percentages equals the overall percentage.
• Shortfall in questions = (pass % − scored %) × total = (60% − 45%) × 120 = 18.

Common traps

• Averaging 70%, 50% and 30% to 50% when the sections have 20, 50 and 50 questions.
• Adding each section's gap to 60% (5 + 15 = 20) and ignoring GK's surplus of 2.

No directly related past PYQ was found.