The following table shows the number of voters at 5 different centres P, Q, R, S and T and the percentage of people who voted in an election.
| Centre | Total Number of Registered Votes | Percentage of People Who Voted (Out of the total number of registered voters) |
| P | 3500 | 85% |
| Q | 2900 | 76% |
| R | 2400 | 82% |
| S | 1850 | 90% |
| T | 3000 | 87% |
If the number of invalid votes cast at Centre S was 20% of the total number of votes cast, then what percentage of the total number of registered voters cast invalid votes at Centre S?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 18%.
Total registered voters at Centre S = 1850
Percentage who voted = 90% of 1850 = (90/100) × 1850 = 1665 votes cast
Invalid votes = 20% of 1665 = (20/100) × 1665 = 333
Percentage of total registered voters who cast invalid votes = (333 / 1850) × 100 ≈ 18%