Shortcut Trick
Valid votes received by Q can be directly found using successive percentage multipliers.
Q's Valid Votes = Total Electorate × Polled % × Valid % × Q's Share %
⇒ Q's Valid Votes = 75,60,000 × 90% × 85% × (100% − 78%)
⇒ Q's Valid Votes = 75,60,000 × (9 ÷ 10) × (17 ÷ 20) × (11 ÷ 50)
⇒ Q's Valid Votes = 7560 × 9 × 17 × 11 = 12,72,348
∴ The correct answer is 12,72,348.
Alternate Method
Given:
Total votes of the electorate = 75,60,000
Percentage of voters who did not vote = 10%
Percentage of invalid votes = 15%
Percentage of valid votes secured by P = 78%
Calculations:
⇒ Number of votes polled = (100% − 10%) of 75,60,000
⇒ Number of votes polled = 90% of 75,60,000 = (90 ÷ 100) × 75,60,000 = 68,04,000
⇒ Number of valid votes = (100% − 15%) of 68,04,000
⇒ Number of valid votes = 85% of 68,04,000 = (85 ÷ 100) × 68,04,000 = 57,83,400
⇒ Since P got 78% of the valid votes, Q must have received the remaining valid votes.
⇒ Percentage of valid votes Q received = 100% − 78% = 22%
⇒ Number of valid votes Q got = 22% of 57,83,400
⇒ Number of valid votes Q got = (22 ÷ 100) × 57,83,400 = 12,72,348
∴ The correct answer is 12,72,348.
Additional Information
Successive Percentage Method
When a base value continuously undergoes percentage reductions or increments sequentially, the final value can be obtained via a single chain product: Base × (1 ± R1/100) × (1 ± R2/100).
Election Base Shifting
It is crucial to remember that the percentage of invalid votes is calculated strictly on the 'Polled Votes', not on the 'Total Electorate'. The base automatically changes after every reduction in real-time election distribution problems.