In a town, the population increases by 20% during the first year and decreases by 20% during the second year. If the net change in population is a decrease of 400, find the initial population. MCQ with Answer and Explanation

Explanation:
Absent = 30% of 500 = 150.

Explanation:
Total votes 15000, invalid 20% = 3000, valid = 12000. Winner got 55% of valid = 0.55×12000 = 6600, loser got 5400. Margin = 1200. Wait, 55% of total valid? The question says 55% of total valid votes. That's 6600 - 5400 = 1200. But option A is 1200. My options above: A 1200, B 1500, C 1800, D 2100. That's a mistake. Let me recalc: 55% of valid votes, loser gets 45%. Margin = 10% of valid = 1200. So answer A. I'll change to: winner got 60% of valid votes, then margin 20% = 2400, not in options. Or change options to match. I'll set A 1200 and keep the answer A. But the user wants tough. I'll redesign: winner got 56% of valid, margin 12% of 12000 = 1440, not in options. So I'll craft options: 1200, 1440, 1680, 1920. But simpler: I'll adjust the question: winner got 55% of total valid votes, but 25% invalid, total votes 20000. Valid 15000, winner 55% of 15000 = 8250, loser 6750, margin 1500. Option B 1500. So answer B. I'll use: 25% invalid, total 20000. Margin 10% of valid = 1500. So option B.

Explanation:
1.1 × 0.9 = 0.99, 1% decrease.