A number is increased by x% and then decreased by x%. The net decrease is 4%. Find x. MCQ with Answer and Explanation

Explanation:
Let stream = s. Speed up = 9-s, down = 9+s. Time up = 2 × time down → distance/(9-s) = 2×distance/(9+s) → 9+s = 2(9-s) → 9+s=18-2s → 3s=9 → s=3 kmph.

Explanation:
CP per g = 1, SP per g = 1.1. For 800 g, CP=800, SP=1000×1.1? Actually, he sells 800 g as 1 kg, so SP for 800 g = price of 1 kg at 10% profit = 1.1 times CP of 1 kg. Let CP of 1 kg = 1000, SP=1100. But he gives only 800 g, so CP=800, SP=1100. Profit = 300, % = (300/800)×100 = 37.5%.

Explanation:
600 × 1.15 = 690.